Marvel is suing to keep the rights to superheroes including Spider-Man, the Fantastic Four and X-Men.

The federal lawsuit filed Friday in Manhattan asks a judge to invalidate notices sent by the heirs of artist Jack Kirby to try to terminate Marvel’s copyrights.

The heirs sent notified several companies last year that the rights to the characters would revert from Marvel to Kirby’s estate.

The lawsuit says Kirby’s work on the comics were “for hire” and render the heirs’ claims invalid.

Comic book characters such as Spider-Man and the X-Men have become some of Hollywood’s most bankable properties in recent years.

Marc Toberoff, an attorney for the Kirby heirs, said he hadn’t seen the lawsuit and had no immediate comment.