How do you define a minor character?

Here's what it isn't: the guest star who leads the story. In Star Trek, that rules out, say, Michael McKean in that creepy Voyager episode where he plays the nightmare clown, or Harry Mudd from the original series. Same for Q. They're all captivating, but each one's episode (or episodes) put them front and center, so they're not on the list.

We're honing in on the smaller roles, where someone was not the major player in the story, but somehow managed to get the attention anyway. In a franchise that's already full of some of the most fascinating characters in television, standing out is no easy task. (And yes, we're sticking to the TV series, or we'd have included Christian Slater's totally random cameo in Star Trek VI: The Undiscovered Country.) Everyone who made it on this list has something striking about them, so here they are: 17 Minor Characters On Star Trek Who Stole The Show.

17. Dwayne "The Rock" Johnson as the Pendari Champion

Johnson is always on the list of "who knew?" guest stars on Star Trek, and for good reason; he went from being a WWE star to becoming the highest paid actor in the world. But when he was still a wrestler, and Star Trek: Voyager and WWF Smackdown were the flagship shows of the now-defunct UPN network, execs suggested putting him into an episode to combine their two most valuable properties. It worked: that episode, "Tsunkatse," was the highest-rated one of the entire season.

The writers managed to come up with a semblance of a story for this one. Seven of Nine is kidnapped and forced to participate in a dangerous, competitive sport against her will. At her first big match, with all the trappings of a WWE bout, the fighters are introduced and out comes Johnson, looking like a mountain of an alien, with a few forehead ridges for good measure. While she's fighting him, the crowds roar, and the audience at home stared in wonder as the WWE's biggest star fought an actress who spent most of her time in a catsuit and high heels. The Rock gave some of his signature moves, and kicked Seven's butt. Better luck next time.

16. Bebe Neuwirth as Lanel, Who Wants "First Contact"

This episode, "First Contact," is full of big moments. Riker goes undercover to observe a pre-warp civilization and determine if they're ready for first contact, but he gets injured and taken to the hospital, where doctors soon discover that he's an alien, surgically altered to look like a native. The main guest star is really Carolyn Seymour (a frequent Trek actor) as Mirasta Yale, the scientist who (like Star Trek's audience) has been "prepared for the realities of space since I was nine years old."

But it's Bebe Neuwirth, famous to TV viewers as Lilith on Cheers and Frasier, who steals everybody's thunder. She plays a nurse at the hospital who offers to help Riker escape. She tells him she can get him out of the hospital, but only if he makes love to her. What?

Yup! In a plot twist that would have been totally different had the genders been reversed (and probably if it had been anyone but that slutty-but-you-love-him-for-it Riker), she trades him her help for sex. Mirasta has always wanted to explore, but Lanel's goal is a little different. "I've always wanted to make love with an alien," she tells Riker, looking up at him longingly.

15. Molly O'Brien

Kids can make or break a scene, on a TV show. Sometimes on Star Trek, they're just annoying - if anyone's seen the "When The Bough Breaks" episode of TNG, they already know that. But Molly O'Brien, played by Hana Hatae, was a scene stealer—in a good way—for two reasons: one, she had a very distinctive, ear-catching voice, and two, she reminded us that the stakes could be very personal.

Miles O'Brien and Keiko Ishikawa got married on TNG, and Molly was born on the Enterprise. When the family moved to Deep Space 9, Molly came along with them, and we finally saw what it was like to be a Starfleet officer with a little kid at home. Wesley Crusher and Jake Sisko don't count, as they were already teenagers when we met them.

Here's a prime example of how Molly raises the stakes: in "Assignment," Keiko's body gets possessed by an alien. All Molly has to to is appear in a scene with her, and the potential danger to the station pales in comparison to the image of this kid with her mother, who isn't her mother, oblivious to the peril she's in. When we see fake Keiko with her hands on Molly's shoulders, it gives us the chills. Molly, just by being there, gets all of our worry, and all of our attention.

14. Sonya Gomez, Recent Academy Graduate

All the Star Trek series usually focus on their seasoned officers, occasionally adding in a younger character to benefit from the wisdom of his or her older colleagues. In "Q Who," though, we meet Sonya Gomez, a recent Starfleet Academy graduate who's working in engineering under Geordi La Forge and couldn't be more excited about it.

When La Forge suggests that walking around Engineering with a cup of hot chocolate isn't the greatest idea in the world, she's mortified. Still caught up in her excitement about her new gig, she walks towards the door but doesn't look where she's going, and collides with Picard, who's on his way in. The hot chocolate spills all over his uniform, and she vainly attempts to try to do something about it by wiping it off him with her hands. Clearly, this is not going to accomplish anything, but she's so embarrassed that she keeps trying. He finally stops her and suggests it would be much easier if he just changed his uniform.

Way to make a first impression... both on Picard, and on us.

13. Morn

Morn was the silent, hulking figure with a permanent seat at Quark's bar on Deep Space 9. Appropriately, his name was an anagram of Norm, George Wendt's character on Cheers who sat on the same bar stool day after day, season after season. Despite never saying a word, Morn appeared in 92 episodes of the show--more than regular character Jake Sisko--and his off-camera activites became a running joke throughout the series. The viewers never saw him do anything other than sit and drink, but he was always talked about as if he had a rich, vibrant life beyond the bar. Worf called him an excellent sparring partner, Dax admitted to an unrequited crush, and Sisko trusted him so much, based on their five-year friendship, that he once saved the Alpha Quadrant based on an encoded message from him.

We don't know much about him, except that he's a Lurian, he slept in mud, he owns a cargo ship (that he occasionally sleeps in), and that he staged his own death to catch a group of thieves after his money. He kept a secret retirement fund of liquid latinum, which he revealed was stored in his second stomach after returning to the station once the thieves were out of the way. He thoughtfully regurgitated some of it as a thank you gift for Quark.

12. The Bartender in "The Trouble With Tribbles"

"The Trouble With Tribbles" is one of the most famous Star Trek episodes of all time, and it's chock-full of memorable characters. That's why we have to give a nod to the nameless bartender of Station K-7. The man was background in the best bar fight scene in the entire franchise, does most of his scenes with the colorful and garrulous Cyrano Jones, and still manages to remain memorable 49 years later.

He barters and banters with Jones, turns his best salesman's smile on Uhura, and generates facial expressions that would make him the star of a silent movie. Later, when Jones tries to sell him tribbles again, he piles them on the bar, one by one. When the fight breaks out between the Klingons and the Enterprise crew, he sweetly stashes all of his troublesome tribbles under the bar to protect them, then tip-toes and almost dances his way out of the room to safety. And in a last-minute move, he yanks the drink out of Jones' hand, smooth and deft, once the fight is over.

The last time we see him, he's slumped at his own bar, surrounded by a pile of tribbles, with a particularly large one sitting on top of his head, and a look on his face we'll never forget.

11. The Pets: Spot and Porthos

Pets have a head start when it comes to scene-stealing, even on Star Trek.

Data's cat, Spot, was in eight episodes of The Next Generation and mentioned in an additional two. Data clearly loves her, and even tries to train her, without much success. She scratches Riker, makes Worf flinch, doesn't get along with LaForge, but takes a liking to Barclay. There's something beautifully distracting every time Spot is in a scene, especially when Data is holding her and petting her. Just like any cat, she needs to be the star of the show, and the way she has Data wrapped around her little orange paw shows that she's a natural.

On to Porthos. For most, Enterprise is not the most memorable of shows. There were some colorful characters: Dr. Phlox was quirky and fun, Hoshi Sato kept things real, and Trip Tucker was one of the most relatable crew members aboard. And then there was Porthos, Captain Archer's dog. We loved that he was always waiting for his Captain to return, loyal and true. Most of all, we appreciate that somebody in the writers' room realized how excellent life would be on a starship if dogs were there. A+.

10. Mr. Homn

"It would be hard to forget Mr. Homn." Jean-Luc Picard

With his tremendous height (7 feet!) and his pale, ashy skin, Mr. Homn doesn't need flashy behavior to make himself memorable. He appeared five times on Star Trek: The Next Generation, but only spoke once, to thank Captain Picard for the drinks, which he devoured with great gusto. While the dinner guests argued, he stood off to the side, observed by Data as he guzzled one drink after another, apparently unaffected, but clearly amused.

Homn was Lwaxana Troi's valet, sometimes called her manservant, and traveled with her everywhere. He was played by Carel Struycken, known to Twin Peaks fans as The Giant in Dale Cooper's dreams. (We hear he's returning, too, in the 2017 reboot.) The man has presence. If you watch him in any of his scenes, he's always hovering (how can he not?) in the background, making faces, and enjoying the impact of Lwaxana on everyone in the vicinity. Struycken says that Homn didn't speak because he was communicating telepathically with Lwaxana and Deanna; on a planet of telepaths, that makes sense. But Mr. Homn had so much presence that he didn't need to speak to make every scene he was in worth watching.

9. Naomi Wildman

Another kid on Star Trek? Resounding yes to this one, because Naomi Wildman finally gave the girls someone to identify with. The smart, brave kid who can save the ship, the world, the country ... in so many movies and TV shows, that character was always a boy. Then Star Trek: Voyager came along and gave us this smart, ambitious, curious half-Ktarian kid who was fascinated by science and engineering and dreamed of being the Captain's Assistant, even though there wasn't one. She was afraid of Seven of Nine, so she stalked her, taking notes, until Seven confronted her and the two became friends. In "Bliss," they even saved the ship together. One of their strongest connections? They both had ties to Earth they didn't understand, and did not share the rest of the crew's enthusiasm for finding their way back to it.

Tom Paris let her pilot a shuttlecraft, Neelix was her godfather, the rest of the crew gave her in a hands-on education in all of their areas of expertise. Never cloying, never too cute, Naomi was the kid we all wanted to be, and she did it with wits, charm, and a touch of reality. Also, we never got tired of hearing Seven of Nine announce her arrival.

8. Kelsey Grammer as Captain Bateson

Kelsey Grammer doesn't appear until the closing scene of TNG's "Cause and Effect," but he makes an impact, no easy task in a episode that sees the Enterprise destroyed before the opening title sequence. The ship gets caught in a time loop, and we watch the crew relive the same scenes multiple times, each time through just a hair different, until they figure out that the outcome is always their complete destruction. When they finally escape, they discover that they've been caught in the loop for 17 days, and that another ship, the Bozeman, was in the same one for 90 years. But all that plot stuff stopped mattering once we saw the Bozeman's captain on the viewscreen. It was Frasier! From Cheers! Omg!

Interestingly, producers also wanted to book Kirstie Alley, famous to Star Trek fans as Saavik from The Wrath of Khan, to do a cameo in that episode. Inspired by the fact that they were using Wrath of Khan sets, they thought it would be fun to have her standing there behind Bozeman on the bridge. They were both shooting Cheers nearby on the Paramount lot, but scheduling issues prevailed, and it never came to pass. Adding Alley would've been even MORE scene-stealing, but Grammer managed it just fine, all on his own.

7. Miles O'Brien, before Deep Space 9

The first time we saw Miles O'Brien, he was sitting at the helm in the series premiere of Star Trek: The Next Generation, and he didn't get a name or even any dialogue where you could see his face at the same time. Later in the season, he was in gold uniform, standing at the transporter controls, and all we knew about him was that he was an Irishman with a twinkle in his eye.

Colm Meaney is a charismatic actor, and eventually O'Brien started popping up more and more, until he finally got some of his own storylines. We learned that he'd fought against the Cardassians and still bore the scars. We watched him fall in love Keiko, marry her, and become a father. He knew his way around the transporter, and the engine room. And when he couldn't be contained as a minor character anymore, off we he went to become Chief of Operations of Deep Space 9. Yes! O'Brien was so un-minor that they finally made a him a major and gave him a show. Congrats!

6. Dr. M'Benga, The Slapper

Remember him? He was a doctor who only showed up when McCoy was really, really busy, and he was the Enterprise's resident expert on Vulcan physiology.

When Spock got shot, he was beamed back up to the ship, but McCoy had too much going on on the planet's surface to join him. So M'Benga ran the show, and in a classic scene-steal, had to slap the shit out of Spock to help him recover. To be fair, Nurse Chapel tried to do what needed to be done, but when Scotty walked in and saw her smacking Spock across the face, he yanked her back and restrained her, totally confused by what he was seeing. M'Benga walked in, took in the scene, and stepped up, smacking Spock repeatedly with all of his might. Smack! Smack! Smack! It had to be done. Spock finally stopped him, emotionlessly saying, "That will be quite enough. Thank you, Doctor." (And he meant it, too.)

For a guy who was pretty easygoing in the two episodes he appeared in, M'Benga sure packed a punch.

5. Nurse Christine Chapel

If you watch Nurse Chapel carefully, you'll see that she's almost always up to something.

Never considered a main cast member, but always around thanks to being married to show creator Gene Roddenberry, Majel Barrett is an integral part of the Star Trek fabric. She was the computer voice on multiple series (and may yet be resurrected technologically for the new one, Star Trek: Discovery), she played Troi's over-the-top eccentric mother, Lwaxana, and provided numerous voices for the animated series that aired in the 1970s. But don't dismiss Christine Chapel, just for being quieter than Lwaxana, because Chapel is a star of almost every scene she's in.

Watch her in "Wink of an Eye" when Kirk asks McCoy if he's hallucinating. Watch her in "A Private Little War," holding Spock's hand. See how she looks at Spock every time he walks into a room, how she reacts to everything McCoy says whether she's supposed to be part of the scene or not, and you'll realize that this character is as much a part of the Star Trek fabric as the actress who played her, even when she doesn't say a word.

4. Lieutenant Commander Shelby

Why Commander Shelby? First of all, she had some pretty tough competition in the two-parter "The Best of Both Worlds," which gave us arguably the best cliffhanger in all of Trek's history. Anyone who sat through that long summer after Riker gave the order to fire on the Borg ship carrying a Borged-up Captain Picard would agree. In the middle of an invasion, with tremendous losses within Starfleet (that ended up giving an intense backstory to future Deep Space 9 star Benjamin Sisko), Picard's transformation to Locutus, and the entire free world at stake, Shelby still managed to stand out.

The reason wasn't so much the way she irritated Riker by wanting his job, but the way she added to the tension. Viewers wondered if Riker, who'd been offered his own command, was really going to leave, but even if they knew he wasn't, the whole arrangement felt like a set-up. Was Shelby getting her own show? Was a spin-off coming? Every scene she was in made you think she was going to become a major player in the Star Trek game, which added an edge to all of her on-screen moments.

3. Ruk

It's hard not to steal a scene when you're 6 foot 9, bald, and wearing a giant cape. But there was stiff competition in this episode that told the story of a long-lost fiance, a hot female android, and to mention a constructed duplicate of Captain Kirk that spun around naked on a giant turntable. Somehow, he managed it anyway. Meet Ruk, the android left behind on Exo III by the "Old Ones." Alone for who knows how long, Ruk kept the machines going until Roger Korby showed up, took over, and reprogrammed him to serve. Good idea, until Ruk remembered that the Old Ones grew scared of their own creations and tried to destroy them. Rage built, fueled by some baiting by Kirk, and when the hulking android came towards Korby with hate in his eyes, Korby was forced to destroy him. Oh Ruk, we hardly knew ye!

Ruk's biggest show-stealing moment came when we learned he could flawlessly imitate anybody's voice, from Kirk to the soft, almost porno-voiced, Andrea. He was a first season character in an unspectacular (and poorly titled) episode, killed off before the end of the it, but completely unforgettable.

Fun fact: Cassidy and Carel Struycken (Mr. Homn) both played Lurch in different incarnations of The Addams Family.

Another fun fact: Cassidy was also the voice of the Balok "puppet" in "The Corbomite Manouver."

2. Kevin Riley

"I'll take you home again, Kathleeeeeeeeeeeeen." Who could forget Kevin Riley? He piped his dulcet tones through the entire ship as Kirk fumed, Spock cried, Sulu went after everybody with a sword, and some random crew member painted messages on the walls. He ordered double portions of ice cream for the crew,  He announced there would be a formal dance in the ship's bowling alley—a place we never got to see, alas—and had suggestions for how women should wear their hair and make-up that he wanted everyone to hear. He also pronounced himself Captain.

When a virus infected the Enterprise, making the crew behave as if they were drunk, Kevin Riley got the drunkest, and the most fun. As he drove Kirk mad with his singing and his refusal to leave the Engine Room as the ship headed towards its doom, he made us laugh at the same time. He only had two episodes in the entire series, but we still miss him, and wish he'd stayed.

1. Spock's Beard

Talk about scene-stealing! For Star Trek viewers who aren't fans enough to know that the name of this episode is "Mirror, Mirror," all you have to do is say "Spock has a beard" and they know what you're talking about. Spock's beard is such a character all on its own that there's even a band called named after it, that's been recording and playing for almost 20 years.

This is one of the most celebrated Star Trek episodes up there, definitely in the all-time top five from any series. Kirk, Uhura, Scotty and McCoy -- an odd foursome for a landing party, to be sure -- beam back onto the Enteprise but it's not THEIR Enterprise; it's a warped, twisted version of the world they're used to. They're all wearing gold sashes, Uhura's uniform leaves her midriff exposed (in case anyone had doubts that Nichelle Nichols was in perfect shape in 1967), everyone salutes the Captain, and Spock has a beard. The landing party soon discovers that any action perceived as incompetence or misbehavior is physically punished. After a shaky beam-up, Spock blames Transporter Chief Kyle. "Your agonizer, please." Kyle hands over a small device and Spock uses it to inflict scream-worthy pain on the poor man, while Kirk's eyes widen and Uhura shrinks back.

Even with all of that going on, plus a lecherous Sulu, a sexy "Captain's woman," and a device that can eliminate Kirk's enemies at the touch of a button, it's still Spock's beard that everyone remembers.

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 Okay, who'd we miss? Let us know in the comments.

Star Trek: Discovery is the newest show in the franchise, scheduled for a premiere in May 2017.