You have a great idea for a character name. But there's a problem — someone else had the idea first. And they used it... a long, long time ago. Like, before you were born. The character may not even be that well-known (or known at all) today. Too bad — you missed your chance. Better change the name before airtime, or you'll find yourself knee deep in the paperwork of a trademark infringement lawsuit. If word gets out online, the original name may still be used by the fans. Efforts to have this listed as a violation of intellectual property are no doubt pending. However, certain uses are (at least in the United States) covered under what are known as Fair Use Laws. We have a page about Trademarks if you're really interested in how they work and are used. The same reasoning behind many a Stealth Pun. This is one reason why a character might be Renamed to Avoid Association. Contrast Captain Ersatz, where the writers are trying to use an already existing character but can't. See also Brand X, Bland-Name Product, Disney Owns This Trope, You Wanna Get Sued?, Lawyer-Friendly Cameo, A.K.A.-47, Product Displacement, and Clumsy Copyright Censorship.