In the 1930s, two Jewish boys, Jerry Siegel and Joe Shuster, created the comic book character Superman. In 1938, badly in need of money, they sold the rights to the character for $130, to what would later become DC Comics. Superman was a huge success and generated millions in profit, but his creators got nothing. They sued, but after decades of litigation they lost: The contract they signed was found to be valid. They lived near poverty all their lives.
If they had gone to a bet din, how would halacha view the matter?
(Possible considerations: Is this type of contract valid? Is a contract valid when signed under duress (taking advantage of people in need to buy their stuff for a pittance)? Is intellectual property covered in halacha? There are "finders keepers" rules in Bava Metzia, but can we say the "find" here is the success of Superman? Does DC Comics have an ethical, if not a contractual, obligation?)