Given that many studios often fund films with sequel potential, it isn't surprising to find a follow-up announced way before the first installment has even hit theaters. This, however, does not guarantee that a film will take off. Some sequels, perhaps, are just not meant to be. Either the first film does not perform as well as it should have, or the director has lost the motivation. Sometimes a script has to go through way too many rewrites or maybe the timing just isn't right.

Whatever the reason, the five films listed in this article were potential sequels that, eventually, did not see the light of day.

Return to Casablanca
Back in the day, there was actually an idea for a Casablanca sequel. The beginning of that beautiful friendship that Rick talks about in that final line was almost taken literally, as Warner Bros. began working on Return to Casablanca. In 1980, screenwriter Howard Koch wrote a treatment for the sequel, which followed Ilsa’s son's search to find his father (who was implied to be Rick). Thereafter in 2013, another treatment was discovered by the late Murray Burnett, who originally wrote the play that the film was based on. However, despite several attempts to keep the venture alive, the film never really took off.

Return To Casablanca - BookMyShow

E. T. II: Nocturnal Fears
After E.T. was declared a box-office success, director Steven Spielberg and screenwriter Melissa Mathison began working on an outline for a sequel. Apparently, E.T. II: Nocturnal Fears was not supposed to be light-hearted in any way. In fact, the idea was to have Elliot and his friends kidnapped by a ship of evil aliens, with E.T. setting out to rescue his earthling buddies. However, Speilberg decided to scrap the idea because he thought a sequel to E.T. would do nothing but rob the original of its virginity.

E. T. Nocturnal - BookMyShow

Gladiator II: Christ Killer
Gladiator did not seem like a film that would have a sequel. This is probably because the lead character is buried by the end. However, a continuation almost came into being after Russell Crowe convinced the studio executives to let Nick Cave write a script for the same. In an interview, Cave explained his script. It had Maximus return from purgatory by the gods to kill Christ, who is revealed to be the gladiator’s son and in the end, Maximus becomes an eternal warrior. The studio then shelved the project on grounds of it being too extravagant.

Gladiator - BookMyShow

The Girl Who Played With Fire
Before the adaptation of Stieg Larsson's best-selling novel, The Girl with the Dragon Tattoo, hit the screens, director David Fincher announced that the two sequels, The Girl Who Played With Fire and The Girl Who Kicked the Hornets' Nest, would film back-to-back, with the first sequel nailed down with a 2013 release date. However, the script had several rewrites and the 2013 deadline had come and gone. Later, Sony announced that they would be bypassing both the sequels to adapt the non-Stieg Larsson book The Girl In The Spider's Web.
The Girl Who Played With Fire - BookMyShow

Green Lantern
Ryan Reynolds was supposed to star in three Green Lantern films. However, after the first film was met with negative reviews and also low figures at the box office, those plans were abandoned. Instead, the studio devoted its time working on Man of Steel and the beginnings of the DCEU.
Green Lantern - BookMyShow