Thunderball was always the most controversial of the James Bond films, for reasons that had nothing whatever to do with the subject matter; there has almost always been some sort of litigation connected to the title.
To understand this, we have to go back to before any of the movies were made, to the 1961 novel by Ian Fleming — except that technically it was only partially by Ian Fleming:
Ian Fleming published his novel based upon a television screenplay that he, and others developed into the film screenplay; the efforts were unproductive, and Fleming expanded the script into his ninth James Bond novel. Consequently, one of his collaborators, Kevin McClory, sued him for plagiarism; they settled out of court in 1963.
The settlement, basically, gave Fleming the rights to his novel, and everything else to McClory.
Later, in 1964, Eon producers [Albert B.] Broccoli and [Harry] Saltzman agreed with McClory to cinematically adapt the novel; it was promoted as “Ian Fleming’s Thunderball”. Yet, along with the official credits to screenwriters Richard Maibaum and John Hopkins, the screenplay is also identified as based on an original screenplay by Jack Whittingham and as based on the original story by Kevin McClory, Jack Whittingham, and Ian Fleming. To date, the novel has twice been adapted cinematically; the 1983 Jack Schwartzman-produced Never Say Never Again, features Sean Connery as James Bond, but is not an Eon production.
McClory also got a “Produced by” credit for Thunderball, in exchange for an agreement not to do anything with the intellectual property for at least ten years.
Ten years later, McClory started working toward a remake of the story, with the working title Warhead. It was Jack Schwartzman who did most of the heavy legal lifting to get Warhead made, with an interim title change to James Bond of the Secret Service. The Never Say Never Again title, it turns out, was suggested by Sean Connery’s wife, who recalled that after Diamonds Are Forever he’d said he’d never play 007 again.
In 1997, Sony came up with the idea of a Bond series, starting with Warhead 2000, and paid McClory $2 million to obtain his rights. Lawsuits ensued. Sony settled; the rights remained with McClory, who had gotten the idea that he was entitled to a cut of the entire Bond series. This particular suit was thrown out, but bad blood remained between McClory and Eon — until last Friday:
MGM and the producer of the James Bond movies have finally acquired all of the rights to the 007 franchise. After a legal battle royale that has gone on more than 50 years, the studio and Danjaq [LLC, of which Eon is a subsidiary] today announced they now have all of the rights and interests to the British spy held by Kevin McClory and his estate.
McClory died in 2006 at the age of 80, so the legal unpleasantness actually outlived him.
You’ll remember that Thunderball introduced the fright-inducing organization SPECTRE, headed by Ernst Stavro Blofeld. They’d hang around for a few more films, but eventually weren’t mentioned anymore because of the legal wrangling; a Blofeld-ish character showed up in the pre-title sequence to For Your Eyes Only, but he’s unnamed. Does this mean we’ll see him in another Bond film? I’m with Michelline Connery: one should never say “never again.”