Disney-owned Marvel is suing relatives of Steve Ditko and other Marvel comics creators to retain control of classic characters, including Iron Man, Daredevil, Spider-Man, and Black Widow.

The lawsuits, covered earlier today by The Hollywood Reporter, were filed in New York and California against the heirs of Steve Ditko, Don Rico, Don Heck, and Gene Colan, as well as Stan Lee’s brother and Marvel collaborator Lawrence Lieber. They ask courts to declare that Disney has sole ownership of comics like The Avengers, Iron Man, Amazing Spider-Man, Strange Tales, and Tales of Suspense — including the characters and story elements that have formed the basis for Disney’s lucrative Marvel Cinematic Universe.

As The Hollywood Reporter notes, the suits follow Lieber and others sending termination notices to reclaim part of the rights on many Marvel characters. They’re an attempt to head off litigation that might follow from those notices.

Termination notices are meant to let creators and their heirs share in publishers’ profits. But Disney’s attorneys argue that Marvel had sole creative control over the characters and comic books in question, saying it paid writers and artists on a work-for-hire basis that precluded any rights to the resulting books. “This case thus involves an invalid attempt, by means of termination notices … to acquire certain rights to iconic Marvel comic book characters and stories,” says the suit against Lieber.

Artists and authors, as well as their families, have fought repeated legal battles for the rights to iconic comics characters. The efforts have had limited success. In 2014, Disney and the children of Marvel legend Jack Kirby settled a lawsuit that saw an appeals court rule in Disney’s favor, concluding that Kirby had worked on a for-hire basis. The same year, an appeals court affirmed DC parent company Warner Bros’ victory over the family of Superman co-creator Joe Shuster. And in Marvel cases specifically, the comics giant has cited its collaborative “Marvel Method” as an argument in its favor — saying it makes it difficult to assign ownership to a specific author or artist.