Now in its eighth and penultimate season, Adventure Time has won over young and old fans alike across its plethora of episodes. Thanks to its kinetic animation, absurdist tone, and dense mythology, Adventure Time is like few other shows on television. Most every week, Finn, Jake, and a rotating collection of their friends and acquaintances help save Ooo in between throwing parties, exploring mysteries, and learning more about themselves and each other. Through it all, a sense of heart, humor, and surrealism is woven in to create a unique viewing experience.
More than just visually engaging, the show’s stellar music and top-tier voice cast help bring the show to life during even its most idiosyncratic of episodes. Mixed in with all of the series regulars, however, the show has spent the years bringing on board a number of amazing guest stars. From classic performers to up-and-coming comedians to stalwarts of animation, you may be surprised at some of the people who have lent their voice to the show. And aside from the one-off characters and cameos, you'll be shocked to learn who voices a number of the recurring players.
Here are 15 Actors You Didn't Know Were On Adventure Time.
15 ‘Weird’ Al Yankovic / Banana Man
Best known for his comedy songs, ‘Weird’ Al Yankovic spent the late-80s and early-90s popping up as himself on a number of TV shows in a few movies. It was the early-aughts, however, that opened the door for the performer to begin tackling voice acting.
In 2002, he first leant his voice to The Brak Show on Adult Swim before showing up on everything from The Grim Adventures of Billy & Mandy to Gravity Falls. He’s voiced Darkseid for Teen Titans GO! and even starred in an Animal Man animated series that many a DC diehard have likely never heard of before.
Back in the third season of Adventure Time, he made his debut as Banana Man. Not to be confused with Princess Bubblegum’s Banana Guards, Banana Man is an engineering genius with a love for space travel. Thanks to his skills, he’s been prominently featured in three episodes of the show to date, and is someone we’d love to see get his own spinoff someday.
14 Andy Milonakis / N.E.P.T.R.
Unlike a number of the actors on this list, Andy Milonakis actually plays a regularly recurring character on the show. The comedian first came to public attention thanks to his appearances on The Man Show. From there, his comedic raps kept him in the spotlight and he continued to pop up in various comedies. He even had his own sketch show on MTV for a time in the mid-00s.
Milonakis made his Adventure Time debut back in the show’s first season, in the episode "What Is Life?" When Finn attempts to create the ultimate pranking robot-- a device that throws pies-- some of Ice King’s magic brings the being to life. Dubbed N.E.P.T.R., Milonakis plays a lovable but dimwitted little robot who lives with Finn, Jake, and BMO. He pops up from time to time, reminding everyone that he’s sort of Finn and Ice King’s son, but has recently started showing of his rapping skills alongside Flame Princess.
13 Lena Dunham and Felicia Day / Betty Groff
Lena Dunham spent years making shorts and starring in critically acclaimed indie films before her HBO series Girls made her a household name in 2012. A few\years later, she joined Adventure Time as the voice of Betty Groff, opening up one of the show’s more emotional threads. Simon's ex-girlfriend from the time before Ooo, Betty pops back up on the series as a force of love and chaos attempting to revert the Ice King to the man she loved. Across her three central arcs, she goes from a woman plucked from the past to the wielder of Magic Man’s considerable powers. When it came time for the recent Elements miniseries, however, Dunham’s busy schedule apparently kept her from the reprising the role for Betty’s biggest part yet.
Taking over for Dunham is Felicia Day, the nerd hero who first came to prominence thanks to her role on Buffy the Vampire Slayer. Since then, she’s starred in a number of series, including Supernatural and the cult hit The Guild. There’s no telling if she or Dunham will continue to be the voice of Betty in the future, but Day seems to have the part locked in for now.
12 Ming Na-Wen / Finn's Mom
While Ming Na-Wen is likely known these days to most genre fans as the unstoppable Melinda May from Agents of S.H.I.E.L.D., she actually has a long history of voice work. Just before her huge role on ER, Na-Wen played Chun-Li in Street Fighter before reprising the role in the video game adaptation. In 1998, her voice career really took off when she played the lead in Disney’s Mulan. While she and fans hope to see her get a cameo in the live-action adaptation of the movie, Wen's been pretty busy since then.
She’s had a number of roles on TV, in everything from The Batman to Stargate SGU. Back during the Farmworld episodes of Adventure Time, Na-Wen played that reality's version of Finn’s mother. While she wasn't given a name and hardly resembles Finn's real mother—recently glimpsed in the miniseries Adventure Time: Islands—Na-Wen provided the perfect blend of kindness and toughness the mother of Ooo’s greatest hero requires.
11 Henry Rollins / Bob Rainicorn
Punk icon Henry Rollins will always be best known for his hulking presence and time leading Black Flag, but he’s spent a few decades acting as well. Mostly nabbing small parts, his presence on TV especially has grown in the years thanks to his work on shows like Sons of Anarchy. He’s always had a pretty solid voice acting career as well.
After playing the recurring villain Mad Stan on Batman Beyond, Rollins went on to voice Kilowog in Green Lantern: Emerald Knights and Johnny Rancid on Teen Titans. His most well-known voice role was as the villainous Zaheer during the final two season of The Legend of Korra.
On Adventure Time, Rollins plays the English-speaking voice of Bob Rainicorn, the father to Jake’s beau Lady Rainicorn and the grandfather to their five children. While his takes on villains are fitting, his portrayal of a rainbow unicorn is priceless.
10 Neil Patrick Harris / Prince Gumball
For a certain generation, Neil Patrick Harris will always be best remembered for his work on the late-80s/early-90s drama Doogie Howser, M.D. While that threatened to be his legacy for many years, he was able to climb back from child stardom thanks to a self-deprecating turn in the Harold and Kumar franchise, his work with Joss Whedon on the cult hit Doctor Horrible's Sing-Along Blog, and a starring role in How I Met Your Mother.
He’s also spent years doing voice work, most notably as the star of MTV’s Spider-Man series. He’s popped up twice now on Adventure Time, playing Prince Gumball in Ice King’s Fionna and Cake stories. We haven’t gotten to know the Prince as well as Princess Bubblegum, but hopefully he’ll return next time Fionna and Cake get a spotlight.
9 Alan Tudyk / Chatsberry
Alan Tudyk was working pretty steadily for years before his double-big-break when he landed the roles of Hoban on Firefly and secured multiple voice roles in the first Ice Age. Since then, his voice work has continued, as has his collaborations with Joss Whedon. He recently landed his biggest role, doing the voice and mocap for K-2SO in Rogue One, but his career is littered with dozens of smaller parts and plenty of voice work.
On Adventure Time, he voices the character of Chatsberry. One of the previous Candy Elementals, he first appears in the episode "Evergreen", where we learn the origin of Ice King’s crown, the concept of Gunter/Gunther, and first meet the Elementals. Thanks to season eight’s renewed focus on the primordial forces, Chatsberry has since returned to lend Princess Bubblegum some insight into her past life and her current powers.
8 Ron Perlman / The Lich
Ron Perlman has made his mark thanks to his leading roles in Hellboy and Sons of Anarchy, but his voice is actually one of the most recognizable in all of animation. After a decade or so of film and TV roles, Perlman broke into the voice acting world in the early ‘90s with parts on Animaniacs, Bonkers, and, most notably, as Clayface on Batman: The Animated Series.
Despite his signature tone, however, his work on Adventure Time is almost unrecognizable. Once you learn that he voices the Lich, though, it makes a lot of sense. While he does a great job creating an even more unnerving voice than usual, it’s not surprising that the most evil being in all of Ooo would be portrayed by Ron Perlman. Few others could conjure the gravitas and terror that is required for the Lich’s voice, and no amount of familiarity will keep it from being creepy.
7 Kumail Nanjiani / Prismo
Looking at Kumail Nanjiani’s over sixty credits, it can be easy to forget he’s a relative newcomer to the entertainment world. Working for the past decade as a comedian and popping up in small roles across TV and movies, Nanjiani’s biggest break has come thanks to the hit HBO show Silicon Valley. For Adventure Time viewers, however, he may always be Prismo.
One of the most powerful cosmic beings in the show, Prismo is pretty laid back and a solid friend. It can be easy to forget, however, that he wields enormous power. With the ability to grant wishes, Prismo’s presence on Adventure Time usually indicates some celestial party or an episode like the infamous Farmworld suite, wherein we see a bizarre, alternate reality where the Great Mushroom War was averted but things still went south for the planet.
6 Matthew Broderick / Dream Warrior and the Spirit of the Forest
Matthew Broderick has had a decades long career in theater, film, and television, with a number of iconic roles. One of those happens to be his biggest voice role; playing Simba in The Lion King. Since that time, he’s lent his voice and skills to a number of surprising productions, most notably Adventure Time.
He first popped up as the mysterious Dream Warrior, a used car salesman who helps give Finn and Jake advice while they battle the gargantuan fighter the Farm. Years later, he returned as a similar looking character named the Spirit of the Forest. Appearing in the episode "Flute Spell", the Spirit is alluded to being Huntress Wizard’s former flame, but is friendly to Finn nonetheless.
Given the mystical presence of both characters, and theories speculating they're the same person, we wouldn’t be surprised if Broderick reprised either in the future.
5 Donald Glover / Marshall Lee
In a fitting bit of symmetry, Donald Glover will be playing the voice of Simba in the upcoming remake of The Lion King. Despite years of making shorts with his comedy group Derrick, it wasn’t until Glover’s work on Community that his star took off. Since then, he’s starred in the hit FX series Atlanta, voiced Miles Morales on Ultimate Spider-Man, and will have a small, undisclosed role in Spider-Man: Homecoming before playing a young Lando Calrissian in the Han Solo spinoff film.
On Adventure Time, he’s appeared twice as the gender-swapped version of Marceline, Marshall Lee. Like Marcy, he’s a hip vampire, and he's friends with Prince Gumball and Fionna. While we’ve barely scratched the surface of his character, it would be revealing to learn if he shares a similar past to Marcy but with the Ice Queen, especially as Ice King is the one crafting his tale.
4 Paul Reubens / Dancing Bug
Throughout Adventure Time, there are a number of small creatures and side characters who pop up here and there. The snail is the best known one, appearing in every episode of the show in some shot. When it comes to a big name like Paul Reubens, best known for his character Pee Wee Herman, you would think a sizable role would await him. Of course, you’d be wrong.
For Reubens' only appearance on the show, he plays a character dubbed Dancing Bug. He’s only given this name in the credits, however, and is sometimes called Pincer Beetle in the few other episodes he’s shown up in. During "Power Animal", Reubens voices the little critter who joins Jake in a fervent dance number.
Most of his other appearances are in the background, and when he pops up in "Little Brother", it’s actually John DiMaggio who voices him instead of Reubens.
3 Aziz Ansari / DMO
Like Nanjiani, Aziz Ansari spent the mid-to-late-aughts doing stand-up and small roles. His prominence rose thanks to his MTV sketch show Human Giant, leading to roles on Scrubs, Ice Age, and Judd Apatow’s Funny People. Since then, he’s become a massive name in the world of comedy thanks to his stand-up and starring role in Parks and Recreation and his Netflix show Master of None.
Back in 2013, during the fifth season of Adventure Time, Ansari voiced one of the many robots BMO encounters during his coming-of-age story in "Be More". Ansari voiced DMO, the concierge and greeter for the facility run by Moe, and a rather downtrodden individual at that.
Unfortunately, he doesn’t return for the character’s next appearance, with voice actor Cole Sanchez taking over the role. Of course, with DMO on the verge of death in the episode, you can hardly blame Ansari for not taking the time.
2 George Takei, Levar Burton, and Jonathan Frakes / Ricardio, Bubble, and Adult Finn
Sadly, the various Star Trek stars haven’t all appeared together, but they show how committed Adventure Time is to honoring other genre stalwarts. Just as many Star Trek actors have appeared on Futurama, so too have many of them taken turns on Adventure Time.
George Takei was the first to arrive, voicing the Ice King’s sentient heart, Ricardio, in a number of episodes. Proving more cunning and violent than his previous owner, Ricardio oozes with sleaze and charisma thanks to Takei.
Burton’s role was only a one-off, but a meaningful one. In one of several solo BMO episodes, Burton plays Bubble, the little sphere of air that BMO befriends on their journey back to the Tree House after they’re lost.
Frakes, meanwhile, has voiced an adult version of Finn in two of the show’s weirdest episodes. In both "Puhoy" and "Dungeon Train", Frakes plays the grizzled, older Finn in episodes that see him live out an entire lifetime in the blink of an eye.
Though Bubble may be gone for good, here’s hoping Ricardio and Adult Finn can someday team up.
1 Mark Hamill / Fear Feaster
Like Futurama, Adventure Time has not only featured Star Trek alum but one of Star Wars’ biggest leads as well. Though not a major character, Mark Hamill has turned up three times to play the dastardly Fear Feaster. Sounding quite similar to his work as the Joker from Batman: The Animated Series, Fear Feaster is an evil dark cloud that lives in Finn’s gut.
He first emerges in "Ocean of Fear", where Finn is forced to confront his deep-set dread regarding the sea. Hamill hams it up accordingly, taunting and teasing Finn. He later shows up briefly in "King Worm", fittingly during an intestinal-related scene. Finally, Finn must confront and stop the Fear Feaster in "Billy’s Bucket List", which destroys the character and his future.
Hopefully, however, the show will find another role for Hamill as he’s too good to not return as a voice on Adventure Time.
Which Adventure Time guest stars are your favorite? Let us know in the comments.