- "There’s no Back To The Future IV and there shouldn’t be a Back To The Future IV. I don’t think there should ever be a fourth sequel to anything. Three is a dramatic number. It’s a three-act structure. Four is even. Four is boring."
- —Robert Zemeckis
Back to the Future Part IV is a long-rumored, but consistently debunked, film sequel to the Back to the Future trilogy.
On May 27, 2008, after the opening of the first Indiana Jones film since 1989, cinemablend.com and other sites reported that Bob Gale had ruled out the possibility. At a question and answer session on April 19 at Celebration, Florida, (in conjunction with a benefit for the Make-A-Wish Foundation of Central and South Florida), Gale opened the session with a statement: "Let me answer one question before anyone asks it, which is 'Is there ever going to be a Back to the Future Part IV? No."
Responding to what bttf.com described as "an immediate stream of groans and obvious displeasure from the audience regarding the answer," Gale added, "Well now, wait a minute now. We've all seen, sometimes, where they make one too many sequels, and you say, 'Maybe they shouldn't have done that.' I'm not going to name any names of movies, but you know what they are!"
He added, "But more importantly, as I'm sure you all know, Michael J. Fox is not in the best of shape with his Parkinson's. The idea of making another Back to the Future movie without Michael J. Fox... you know, that's like saying, 'I'm going to cook you a steak dinner and I'm going to hold the beef.' You can't do that."
Gale added, "I'm sure Universal would love it if we were to say to them, 'Hey, let's do another one!' but we don't think we could ever make a fourth one that would live up to how great the first three are, so we're going to leave well enough alone." 
As stated by several of those that made the trilogy, Back to the Future Part IV is not likely to happen, at least not anytime soon.
In reference, an episode of Spin City in which Christopher Lloyd cameoed was titled "Back to the Future Part IV: Judgment Day".
On April 1, 2009, an April Fool's Day joke was created when a story was published regarding news of a BTTF IV in the works.
Once again, in November 2010, Bob Gale spoke to BTTF.com as part of a Myth Debunking story, and restated that both Robert Zemeckis and him "have no plans or desires to make another Back to the Future movie — not a Part 4, or a remake of Part 1." Gale added that "nor does Universal or Amblin have any such plans. How do we know? Because, per our contracts with these companies, no Back to the Future sequel or remake can even be scripted without discussing it with us first. No such discussions have taken place. We are very proud of the Trilogy as it stands and we want to leave it as is."
Many fan contributions have been made to expand the Back to the Future trilogy. One of the most notable is Back to the Future Part IV for Parkinson's UK by Luke Palmer, which goes into the year 2025 when Griff Tannen and Martin McFly, Jr. run for mayor and destroy the city. Palmer continued the series further. Scott Sensabaugh's Back to the Future: Part IV which involves Marty arriving in a new 2015, when Doc had stopped himself from discovering advanced technology as seen in Back to the Future Part II's 2015 due to falling in love, and the effects on their time traveling adventures because of the new future.
Other non-film sequels
There have been commercially-released sequels to the film series, but none have come in the form of a fourth film.
- The amusement park attraction Back to the Future: The Ride presented a limited amount of narrative which took place after the films.
- The cartoon Back to the Future: The Animated Series and its spinoff comic books loosely followed the events of the film series, with a focus on child-friendly jokes and science lessons.
- The computer game Back to the Future: The Game presented a more adult-skewed take on the events following the films.
The canonicity of all of these media relative to the film trilogy is unclear.
Notes and references
- ↑ "BackTalk: Bob Gale dashes any hope for 'Back to the Future 4'", bttf.com, May 25, 2008
- ↑ 'Back to the Future' Myths and Misinformation Debunked November 11, 2010