In 1988, Warner Bros. cast legendary actor Robin Williams as the Joker. Of course, this didn't end up coming to fruition by the time of the film's release. In fact, Warner Bros. had had merely cast the actor as leverage in an attempt to get their top choice, Jack Nicholson, according to Screen Rant.
While examples like this are extremely rare, actors leaving behind a production is not uncommon. It has happened numerous times for a multitude of different reasons throughout the years. Had things gone differently, these films could have turned out completely different.
Chris Farley - Shrek
It's super hard to think of anyone else but Mike Myers as Shrek. He truly makes the character come to life in what is unequivocally one of the best fairy tale movies. However, he wasn't the original choice to play the ogre for DreamWorks. SNL star and comedian Chris Farley was initially hired in the lead role and had recorded most of the dialogue for the film before unfortunately passing away before completion, per CheatSheet.
Mike Myers was then cast and interestingly, he initially voiced the character with a stereotypical Canadian accent before asking to re-record his lines and instead used a Scottish accent. It definitely paid off hiring Myers as the film expanded into a multi-billion-dollar franchise. That being said, it would be interesting to see how the film would have been with Farley.
James Purefoy - V For Vendetta
Based on Alan Moore's iconic graphic novel, V For Vendetta follows V, a revolutionist who creates strategic attacks to ignite a revolution in a Totalitarian London. The role was originally given to British actor James Purefoy, who was involved in the production for six weeks.
Purefoy later left the role due to creative differences, according to Looper. After previously working with producers Joel Silver and the Wachowskis on The Matrix films, Hugo Weaving was hired to take on the role and the rest is history
Tobey Maguire - Life of Pi
In Life of Pi, the role of the writer that meets with the older Pi Patel, was originally played by Tobey Maguire. Maguire had even filmed all of his scenes but was later cut from the final film.
Director Ang Lee chose Rafe Spall to replace him and justified the decision by stating that it was done "to be consistent with the other casting choices made for the film, I decided to go with an entirely international cast", via TotalFilm.
Katie Holmes - The Dark Knight
Following her appearance as original character Rachel Dawes in Batman Begins, Katie Holmes was expected to play the role once more in the film's sequel The Dark Knight. As she was not tied to a contract, Holmes signed on to the film Mad Money, via Business Insider.
By the time filming was coming around for The Dark Knight, she was still busy with her commitments to Mad Money which prompted Warner Bros. to cast Maggie Gyllenhaal to play Dawes. Gyllenhaal truly made the character her own and enhanced the film with her performance.
Harrison Ford - E.T. the Extra-Terrestrial
A timeless classic from Steven Spielberg, E.T. the Extra-Terrestrial originally included a role from a frequent collaborator of the filmmaker. That person was Harrison Ford, per EW.
Ford was picked for the small role of Elliot's elementary school Principal. Upon reviewing E.T. in the editing room, Spielberg decided to cut the scene as he felt Ford would be too much of a distraction from the rest of the film. To date, the scene has never been officially released but some low-quality clips have found their way to YouTube.
Eric Stoltz - Back to the Future
Back to the Future is without a doubt the greatest time travel film of all time. Interestingly, Michael J. Fox almost didn't play McFly. Although Michael J. Fox was always Universal's top choice to portray the character, he was sadly tied with the sitcom Family Ties. Due to this, acclaimed actor Eric Stoltz from the film Mask was chosen in Fox's stead.
Unfortunately, this decision ended up backfiring completely as Stoltz began to become a problem on set, often clashing with Biff actor Thomas F. Wilson due to his strict method acting and even refusing to be called anything but 'Marty', per Vulture. By the time Stoltz was let go, Fox's schedule opened up, thus allowing him to finally play Marty McFly.
Johnny Depp - Fantastic Beasts: The Secrets of Dumbledore
Johnny Depp appears briefly at the end of Fantastic Beasts: The Crimes of Grindelwald as the eponymous villain. However, after receiving abuse allegations from Amber Heard and losing his defamation case in the UK, Warner Bros. made the decision to fire Johnny Depp from The Secrets of Dumbledore after only shooting three scenes, according to THR.
Depp's absence and the search for a replacement caused additional delays which prompted Warner Bros to delay the film from November 2021 to Spring 2022. Eventually, Mads Mikkelsen was cast for the role instead.
Stuart Townsend - The Lord of the Rings
In a case similar to Back to the Future, Stuart Townsend was initially cast as Aragorn even though he was only 27 at the time filming began. After a month of filming, Peter Jackson decided to recast the role as he and the studio felt Townsend was too young, per Yahoo News.
Viggo Mortensen was brought onboard but other actors considered for the role included Daniel Day-Lewis and Russell Crowe. Ultimately, Mortensen was the best choice as Aragorn remains a fan-favorite character from The Lord of the Rings films.
Winona Ryder: The Godfather Part III
Winona Ryder was first cast in the integral role of Mary Corleone for the third and final Godfather film. After filming three other movies back-to-back, Ryder was forced to back out due to nervous exhaustion after collapsing. To recast the role, director Francis Ford Coppola cast his own daughter Sofia, who would later go on to become a filmmaker as well.
Her performance was unfortunately not very good and was extremely poor-received. Despite this, the film still managed to nab seven Academy Award nominations, including Best Picture. To celebrate the film's 30th anniversary, a new cut was created by Coppola which fared much better with critics and was seen as marginally better.
Colin Firth: Paddington
Paddington 2 has been widely considered by many to be one of the greatest films and for the longest time had a 100% approval rating on Rotten Tomatoes. While many have become so familiar with Ben Whishaw as the voice of the lovable bear, he was originally set to be voiced by Colin Firth.
Even a trailer for the film featuring Firth was released but later during post-production, the studio and Firth mutually agreed that his voice just didn't fit with the character, according to BBC News, so instead, they cast the much younger Whishaw.