At this point, it would seem like James Bond has done everything a super spy could possibly do. And yet, the original big screen Bond, Sean Connery, was once involved in writing a James Bond story that never made it to theaters. The movie would have been called Warhead and while it started life as a remake of Thunderball, it would have gone off in some very interesting directions, including robot sharks carrying atomic bombs through the sewers of New York.
The story of Warhead is actually the story of a much better known James Bond story, Thunderball. Back in 1958, before any James Bond novels had been turned into films, a man named Kevin McClory and another screenwriter wrote, with Ian Fleming's blessing, an original Bond story that was going to be the first Bond movie. The movie wasn't made, but Fleming, who had actually been the one to come up with the title, ended up using elements of Thunderball for his own James Bond novel. McClory sued Fleming and won, which resulted in McClory owning the film rights to the story.
When Eon Productions wanted to turn Thunderball into the studio's fourth Bond movie, they made a deal with Kevin McClory that gave him the right to remake the movie 10 years later. Thus, in 1975 work began on the Thunderball remake, which became known as Warhead. By 1975, Sean Connery had already given way to Roger Moore in the role of James Bond and, according to the BBC, McClory wanted Sean Connery's name attached to Warhead in whatever way he could get it, which meant getting him on board as one of the screenwriters.
It's unclear how much Sean Connery actually contributed to the script for Warhead. He has no official film credits as a writer in his career and had never been attached as one before, and would never be again, so it's possible Connery's name was really just there for the press it would generate, but either way, it was there.
While Warhead and Thunderball were still mostly the same story, this new version did see a lot of changes, such as the aforementioned robot sharks and a finale that saw Bond fighting Spectre goons at the top of the Statue of Liberty.
Eventually, just as a lawsuit helped create Warhead, another ended up killing it. Eon Productions and McClory ended up filing injunctions against each other, with each side claiming that the other had stolen material from them. Some elements of the then in production The Spy Who Loved Me were awfully similar to elements in Warhead. Not wanting to get involved in the legal issues, both Sean Connery and Paramount Pictures, who was originally going to back Warhead, backed out, and when that happened Warhead fell apart.
Kevin McClory would eventually get his Thunderball remake in 1983 with Never Say Never Again, but the less said about that, the better.