Marvel has filed five lawsuits in an attempt to block the impending copyright termination of some of its most iconic characters, including Iron Man and Spider-Man.

Per documents obtained by The Hollywood Reporter, the lawsuits were filed against heirs to some of the creators of these characters, most notably Stan lee, Steve Ditko, and Gene Colan. The suits argue that the characters were created as part of “work for hire” arrangements, and suggest that these characters should be exempt from copyright termination as a result.

The documents cite a case involving Jack Kirby, one of the most important creators in the world of comic books. In it, his heirs attempted to reclaim copyright ownership of his creations, which include The X-MenThor, and Iron Man among others. Federal courts ultimately sided with Marvel in that case, deciding that characters were created as part of the aforementioned “work for hire” arrangements. Lawyer Daniel Petrocelli said that case and the new cases come under “virtually identical circumstances.” 

The lawsuits filed on Friday were filed specifically against Lawrence D. Lieber, Patrick S. Ditko, Michelle-Hart Rico and Buz Donato Rico III, Keith A. Dettwiler, and Nanci Solo and Erik Colan. As part of the Copyright Act of 1976, heirs can terminate a license or transfer the rights of copyrighted work if done through a properly executed notice. All of those named in the lawsuit have applied for the copyright termination of characters including Falcon, Captain marvel, Iron Man, Black Widow, Spider-Man, and Doctor Strange.

If Marvel and its parent company Disney lose the lawsuits, it’s likely the company will lose full ownership of the respective properties and characters. Marvel will at least hold on to rights as co-owners, however, but the studio would be forced to share profits. The copyright termination would only apply in the United States, too, meaning Disney and Marvel will retain full control and profit from foreign distribution.

Steve Ditko is the co-creator of Spider-Man and Doctor Strange, and his estate filed the notice of copyright termination this week. Filed by Patrick S. Ditko, his brother, the notice of termination gives Marvel an end date of June 2023. When Ditko died back in 2018, reports indicated that his estate was worth only $1.3 million despite co-creating one of the world’s most famous characters in Spider-Man.