Some of the biggest names in comic book history, from Spider-Man and the Incredible Hulk to the X-Men and Fantastic Four, have found themselves locked in a new battle over who owns their copyright. The superheroes have been invoked by the heirs of the comic-strip artist Jack Kirby, who died in 1994 after being involved in the creation of dozens of popular characters. Kirby’s four children have lodged 45 notices of termination of copyright by which they would acquire their father’s share when it comes up. Under America’s complicated copyright laws, the rights for the Fantastic Four, for example, would come up in 2017, the Hulk in 2018 and X-Men in 2019. If the children win their claims, they will then hold their portion of the rights for the following 39 years before the characters become open public property. Victory in the claims would give the children rights to a share of the profits from any film or other spin-off made from the characters, and they could even sell the rights themselves, independently of Marvel or any of the big studios. The new claims have implications for a large number of media companies, including Sony Pictures, which owns film rights to Spider-Man, Universal, which has distribution rights to Hulk films, and 20th Century Fox, which owns film rights to the Fantastic Four and X-Men. The company that stands to lose most is Disney, which has just agreed to buy Marvel for $4bn (£2.5bn). Disney has said that it entered into the deal in full knowledge of the Kirby claim. As the legal case progresses, interested parties will have to decide to what degree Kirby was responsible for the creation of the Marvel characters. Kirby worked closely with Marvel’s editor-in-chief, Stan Lee, and together they also devised Mighty Thor, Iron Man and the Avengers.