(Under U.S. copyright law, authors or their heirs may reclaim rights from publishers after a certain number of years.) If successful, these notices would allow Marvel to continue using the characters, but require the studio to share ownership and profits with the creators' heirs.
Among those seeking termination are the estates of Marvel Comics legends Steve Ditko (co-creator of Spider-Man and Doctor Strange), Don Heck (co-creator of Iron Man, Black Widow, and Hawkeye), Don Rico (co-creator of Black Widow), and Gene Colan (co-creator of Falcon, Captain Marvel, and Blade), as well as Larry Lieber, co-creator of Iron Man, Thor, and Ant-Man and the younger brother of Stan Lee.