In 1981, Nintendo was gaining success in America with its arcade hit, Donkey Kong. Universal was relatively unaware of this until the Donkey Kong brand gained traction, with its own breakfast cereal becoming popular and other companies wanting to make a version for home consoles.
Universal asked Nintendo to pay royalties, arguing that the arcade game was similar to its hit movie franchise King Kong, which they owned the rights to. Nintendo, being a relatively small company at the time, refused to pay royalties -- and on June 29, 1982, Universal City Studios filed a lawsuit against them.
Nintendo hired John Kirby to represent the company in court. And Kirby managed to prove that Universal did not own the rights to King Kong by going through Universal's own litigious history! Before Universal could remake King Kong in the 1970s, they had to go to court to prove that RKO Pictures (the makers of the original 1933 film) did not own the rights to the brand, which was in the public domain.
The creator of Donkey Kong, Shigeru Miyamoto, also explained in court that the character was originally called King Kong, as that was a generic Japanese term for "menacing ape". The final nail in the coffin came for Universal when the arcade games were played in court. They bore no resemblance to the King Kong movies -- and even if they did, Universal had gone out of its way in another case to prove this was in public domain.
This case is often used as a study for the public domain defense in copyright law. And it proved that even a small company can get its way. Nintendo was offered $1.8 million in damages, and there are rumors that its popular character Kirby is named after the lawyer who helped them win against Universal.