If you can think back on all your favorite shows, every character you've sympathized with and every actor that left midway through the series, then you will recall how each of those series changed since their first episode. Things rarely stay the same years later. If they did, shows would never wear out their welcome and the golden age of television would have many more series hovering around double digit series runs. But lucky for us, characters do go through major changes and seasons take unexpected turns. These series, however, didn't even make it past the pilot before they were retooled in a major way for audiences.

We like to think of the pilot episode as a way to test the waters. Committing to watching a new show is a tough decision. You're potentially setting yourself up for hours of invested time, only to risk the chance of being disappointed by the series' end. So the pilot has to be ready to make a great first impression. These shows all went back and corrected their mistakes, eventually hitting the nail on the head and becoming hits. But their pilots were far from perfect.

Here are 11 TV Pilots That Are Drastically Different Than The Show You Know.

11. Three's Company

The third time really was the charm for Jack, Janet and Chrissy when Three's Company first landed at ABC. Once the network decided to to adapt the '70s British sitcom Man About the House for American audiences, it took two failed attempts before they finally got it right.

The only constant that remains throughout the three pilots is John Ritter and Norman Fell as the apartment's new tenant and his cheap landlord. In the first unaired pilot, Ritter plays an aspiring filmmaker named David Bell trying to make it big after moving to North Hollywood. He moves into the Santa Monica apartment with a brunette named Jenny and and a blonde named Samantha, played by Valerie Curtin and Suzanne Zenor. Both would later be replaced by Joyce DeWitt and Suzanne Somers after it was said that both actresses lacked chemistry with Ritter. Fell's character would also undergo a name change from the less appealing George to Stanley Roper.

Although the second unaired pilot would finally get the casting right for Janet with DeWitt, the role of Chrissy was still up in the air. Suze Lanier-Bramlett was cast in the part, but still lacked the charm and naivety that the show's producers were looking for. Somers was cast days before the series was finally picked up. The premiere episode would finally be broadcast on March 15, 1977 with the show's big three in place. Three's Company would have a long eight season stint before finally coming to an end, a result which may not have happened had the casting never come together.

10. New Girl

Sometimes actors get replaced. It's understandable. Things don't work out. Maybe the chemistry on set was off. But there's a difference between recasting someone and completely removing them from the equation. For New Girl, the character with the short end of the stick was Coach (Damon Wayans Jr.), an abrasive and occasionally obnoxious sports fanatic who expressed his feelings with a short burst of yells rather than a calm and collected inside voice. When he appeared alongside Nick and Schmidt as the third male roommate set to share an apartment with the bubbly Jessica Day, the wheels were seemingly set in motion for the show's offbeat quartet. Instead, another character would be introduced to the fold.

When the second episode premiered a week after the pilot, there had to be some initial confusion surrounding the disappearance of one of the show's leading characters. Coach is nowhere to be seen, and in his stead is Winston, Nick and Schmidt's former roommate who has just returned from playing basketball abroad. Since then, Coach has returned, only to leave again. In reality, it was Waynes' obligation to Happy Endings, the short-lived ABC sitcom which ultimately prevented him from sticking around. The character would have provided a much different dynamic to the show had he stayed.

9. Gilligan's Island

The unaired pilot for Gilligan's Island is as lost as the Skipper, Gilligan and the rest of the castaways of the S.S. Minnow were after crashing in the middle of nowhere. First filmed in November 1963, the cast had quite a different look from the faces of the island we know today. The Professor was played by John Gabriel while Ginger was played by Kit Smythe, and Mary Ann was a character known as Bunny, played by Nancy McCarthy. CBS would greenlight the show despite ordering a new pilot with a new set of actors cast in the three roles. The unaired episode, titled "Marooned," wouldn't be broadcast on television for another 30 years. It finally premiered on October 16, 1992.

With Russell Johnson, Tina Louise and Dawn Wells joining the cast as regular members, the series would run for a total of 98 episodes over the course of three seasons. The theme song, "The Ballad of Gilligan's Isle," was later added to the revamped version of the show after the calypso theme from the first episode felt out of place. "Marooned" was forgotten over its thirty year absence, but would resurface when the footage was found by someone working for the TBS channel. Today, the episode is still available for viewing, officially included on the show's first season DVD.

8. 30 Rock

Once the unaired 30 Rock pilot began making the rounds at NBC, it was clear it had all the makings of a hit. The show had some serious star power, a strong writer in Tina Fey, and enough on-screen chemistry to deliver some of the finest laughs seen on the silver screen in years. But not everyone was so lucky to ride the pilot episode to seven seasons of accolades and glowing critical reception. Rachel Dratch, best known for her seven years on Saturday Night Live, would later lose her role as Jenna DeCarlo to Jane Krakowski, who would go on to be nominated for four Primetime Emmys for her performance.

The role of Jenna DeCarlo had a different look from the character that would become Jenna Maroney. She was a much more unconventional host to the fictional sketch series "The Girlie Show." DeCarlo briefly mentions the likelihood of her success in the unaired pilot, expressing her happiness for living in New York and having her own series. Unfortunately, NBC felt Dratch had neither the look nor the appeal of the rest of the cast. In an attempt to keep her on board, Fey gave Dratch recurring cameos. She would appear as numerous characters over the seven season run, raking up 16 episode credits in total. Unfortunately, none of the characters stayed on for long stints or amounted to more than brief appearances.

7. Full House

Being the man of the house is a full-time responsibility, especially when you're a single father. It takes the right kind of person to step up and deliver those tokens of wisdom to their children when their most needed. As it turns out, Bob Saget was the man who stood up to the plate when everything was most in jeopardy at the Tanner household. There was another, lesser known name, however, who almost had the job. That name was John Posey, and if the story is true, he was closer than many would think to becoming the lead of Full House.

The unaired pilot is essentially the same as the premiere episode we know today. In fact, every scene that featured Posey was reshot with Saget and recreated to a T. Then what was the big difference with casting one actor as opposed to the other? Posey simply didn't have the acting experience or the comedic timing during his scenes with his co-stars. Saget had the fatherly demeanor that looked like he could give you a stern talking or reward you with ice cream for doing your chores. Posey had just shot his first pilot episode after having only been a part of a comedy group, and it seemed he needed time to get adjusted to the dad life. But by the time he was ready, Saget's morning show The Morning Program was cancelled and he was free to join the cast. Posey lost out on the role and Saget went on to become one of TV's most memorable dads.

6. The Big Bang Theory

Nine seasons strong and still going, it's hard to imagine The Big Bang Theory could've ever been different. It all started as a simple girl next door story. Two theoretical physicists living together in a small, two bedroom apartment in sunny Pasadena, California meet their new neighbor, a vivacious young blonde named Penny who becomes the girl of Leonard's dreams. But the anchor that tethers Leonard and Sheldon to the real world, effectively removing them from their sheltered lives, almost never came to be.

The original unaired pilot was passed up by CBS, who thought the idea had promise but lacked the proper execution. Kaley Cuoco, who would go on to play Penny, wasn't in creator Chuck Lorre's original version. Instead, the plot revolved around another blonde named Katie (Amanda Walsh), who Leonard and Sheldon take in after witnessing her crying from a recent breakup. Without anywhere to go, she moves in with them despite Sheldon's objections. The pilot also had another character, a colleague and friend named Gilda (played by Iris Bahr) who has a crush on Leonard and whose role as romantic interest would later be given to Penny. Sheldon also does a complete 180 from the version seen in the episode, which opens with him visiting a sperm bank and acknowledging his preference for women with big butts. Luckily, Cuoco would later be added to the cast and Jim Parsons would become the compulsive asexual audiences came to expect.

5. Saved By the Bell

Before Zack Morris, A.C. Slater, Kelly Kapowski and the rest of the gang were roaming the halls of Bayside High, there was Good Morning, Miss Bliss, which featured only a handful of kids from Saved By the Bell. Originally started as its own show, the first episode of Miss Bliss is now considered the beginning of the series. But the original unaired pilot had few of the cast members from either Bell or Miss Bliss. The only actress from either show to feature in the pilot was Hayley Mills in the titular role as a newlywed teacher splitting time between her professional career and her husband Charlie.

The episode featured a pre-90210 Brian Austin Green as Adam Montcrief, a serious teenager who wore suits to school and had none of the scheming characteristics of Zach Morris. Jaleel White (Steve Urkel of Family Matters) also featured prominently in the pilot as the wisecracking Bobby Wilson. NBC would ultimately pass on the pilot and restructure the show with the Bell kids attending the fictional John F. Kennedy Junior High in Indianapolis. Miss Bliss would have a limited 13 episode stint before NBC pulled the plug. Taking notice of the supporting cast, the show resurfaced as the one we know today, now set in Los Angeles. Miss Bliss was removed from the cast and the kids took over as the central characters, leaving audiences with one of the best depictions of high school life in television history.

4. Buffy the Vampire Slayer

Looking back at the seven season run of Buffy, the premiere season is mostly a blur of lackluster "monster-of-the-week" episodes and poorly strung together attempts at character development. It took the first year for Joss Whedon to fully develop the show's central three characters — Buffy, Xander and Willow — into the evil-suppressing Scooby Gang seen in the later seasons. Still, the pilot Whedon used to first pitch Buffy to Fox was something altogether different from what fans came to know and love about the teen drama.

Before the show ended up in the hands of the WB network, it was making the rounds with a brunette Sarah Michelle Gellar in the lead role. The unaired pilot was a half hour long, which opened without a theme song and presented the show's cast as students at Berryman High School. Many notable faces from the Buffyverse would all make appearances, including Angel, Darla, Harmony and actor Danny Strong, who later would be cast as Jonathan Levinson. The fictional punk rock band, Dingoes Ate My Baby, which would later serve as an introduction to Willow's werewolf boyfriend Oz, even gets a brief mention as the headliner at The Bronze. But the biggest change came with the absence of Alyson Hannigan, the face we all came to recognize as the vulnerable, red-headed witch-to-be. She would be portrayed by the unknown Riff Regan before being recast.

3. Seinfeld

No Elaine? Kramer's name is Kessler? The show is called The Seinfeld Chronicles? There's a dog? What is this madness?

Unfortunately, this is one pilot that was a reality for everyone who tuned into the premiere when it aired on NBC in 1989. When the show polled negatively with test audiences, a first season pick up wasn't the result the studios had in mind. As a last ditch effort, The Seinfeld Chronicles was broadcast and received positive reviews from television critics, who believed the show had potential to continue as a full series. With a four episode order, the rest was history and one of television's greatest success stories soon followed.

When NBC first funded the show, it was with the promise that there would be a female lead to back the all male cast. That lead for the pilot was Claire (Lee Garlington), a waitress that worked at Pete's Luncheonette, Jerry and George's hangout before the name was changed to Monk's Cafe. She would later be replaced by Julia Louis-Dreyfus when the producers decided a waitress wasn't the most interesting profession for a leading character. The episode also featured Kramer, who was referred to as Kessler and owned a dog. The dog was later removed from the show and the title of course shortened to Seinfeld. With a change to the intro and new music to boot, the show picked up publicity and sustained its premise for nine seasons.

2. Star Trek

Depending on who you ask, the true pilot of the original Star Trek series is open to interpretation. We can't blame true Trek fans for sticking to their phasers when it comes to claiming "Where No Man Has Gone Before" as the pilot for the series. It was the first episode to be shot under Lucille Ball's Desilu Studios that would actually air during the show's first season on NBC back in 1966. But unless we can erase the past, there is no denying that the first episode of Star Trek was actually "The Cage," a rejected pilot deemed too cerebral and poorly paced for network television.

The unaired pilot followed Captain Christopher Pike and the rest of the Enterprise crew en route to the Vega Colony in order to aid wounded crew members. The pilot was considered risque, featuring a sequence with a half-dressed dancing green alien, and James Tiberius Kirk was nowhere to be found. The pilot did feature Leonard Nimoy as Spock, but he was neither the First Officer nor the logical thinker he proved to be in the series. With "Where No Man Has Gone Before," Pike was removed and William Shatner took over the lead role from actor Jeffrey Hunter. "No Man" would later be broadcast as the third episode of the first season and would prominently feature recurring characters absent from the original pilot, such as Montgomery Scott and Lt. Sulu. "The Cage" would go on to be broadcast for the first time on television in full color on November 27, 1988.

Hopefully, the upcoming series has an easier go of things out of the gate.

1. Game of Thrones

When Game of Thrones was still nothing but a pitch idea for HBO, Tom McCarthy, the guy best known for directing Spotlight, traveled to Scotland and Morocco to shoot a pilot that still hasn't seen the light of day. McCarthy would leave the show to work on his movie Win, Win, and shortly after showrunners Dan Weiss and David Benioff brought in Tim Van Patten to direct the premiere episode. Weiss and Benioff have been open when it comes to talking about the lessened quality of the original pilot. The biggest struggle with the show's first attempt was largely in the writers' room, where many crucial details from George R.R. Martin's first book, such as Cersei and Jamie's sibling relation, were left out completely.

According to Weiss and Benioff, so many elements from the original pilot were changed that the premiere looked like a polar opposite in comparison. There was a flashback sequence showing the death of Rickard and Brandon Stark, Ned's father and brother killed by the Mad King. There was also a scene which showed the death of Jon Arryn, the hand to King Robert Baratheon who was seen as a corpse in season one. But the biggest difference was in the casting choices for Daenerys and Catelyn Stark, who were first played by Tamzin Merchant and Jennifer Ehle, respectively. With 90 percent of the pilot reshot to fix the original's mistakes, Weiss and Benioff decided to give some new faces a stab at the female leading parts. Clarke landed the role along with Michelle Fairley, and everyone averted a near disaster which could have ended the worldwide sensation before fans got a first look.

BONUS: Archer

https://www.youtube.com/watch?v=aFd-PhcrFiE

Typecasting is a major downer in Hollywood. Actors can have a hard time making it to the small screen if they're constantly subjugated to playing a specific role. This is an issue Velociraptors know all too well. Everyone thinks they're nothing but roars and sickle-shaped claws, but there's so much more to them than that. They were made to act. The dinosaur in the unaired pilot of Archer only wanted a chance to prove himself. If only it would have panned out, then there would be less discrimination against raptors on television.

Archer's dinosaur-less pilot episode "Mole Hunt" debuted on the FX network on January 14, 2010 with the show's titular character working as an agent for the International Secret Intelligence Service (ISIS). The unaired version of the pilot titled "Archersaurus" was relegated to the special features on the season one DVD. The episode follows the exact plot of "Mole Hunt" with the Velociraptor taking the place of Archer without speaking a single word of dialogue. The running gag continued into the second season with the release of "Archersaurus: Self Extinction," a documentary chronicling the rise and fall of Archersaurus from a famed actor to a heroin addict. Unfortunately, little has been seen from him since.

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Did we miss any radically different pilots from your favorite series? Let us know in the comments section.