Worse case scenario for me would probably be a cease and desist JohnC... as I will probably do it for free at first. Dunno if there is a real calling for anything Centaur. BUT... I can certainly do better than the Protectors comic that featured the Centaur Characters.
Still, the five minutes it'll take you to learn the ropes (and feel free to drop me an e-mail if you need help figuring things out) is well worth avoiding needing to respond to the C&D, in my opinion. And if you check now and a letter does come, you can respond with "show me your renewals, 'cuz they ain't in the CCE," or something more lawyery sounding.
You can't ( apparently) copyright a "character", just the works they appear in, and, presumably the image used to represent them.
Right. Look at the things copyrights cover. They're stories and images (and melodies, but that doesn't help us, here). Nowhere has there ever been a form to register a copyright for Superman. Superman exists because he derives from his stories. (I'd argue that's the take-home point of the cases Ed mentions, that there's a copyright protecting the character, but it's not the character's copyright.)
If I wanted to make a movie featuring DC's "Metamorpho", I'd need to license the rights - what "rights" are they if not copyright? Anybody know how that works? That is, when you get exclusive rights to make a Metamorpho movie, how would that be worded in the contract since you can't copyright a character?
As Ed (again) says, the trademarks, and probably even the right to create a derived work from the copyrighted stories like his origin.
As for any heirs to the original rights holders making a claim, as far as I know, no one popped up during the Protectors run, so they don't seem any more likely to do so at this point.
That's the same legal reasoning that says that, since you haven't been pulled over for speeding on the Interstate, yet (or haven't gotten a ticket for parking someplace), it must be legal.
In trademark law, yes, you can make that argument. An undefended trademark is officially abandoned. Copyright, however, is a monopoly on the work to be handled as the owner likes. If he's OK with competition, he can neglect it and then crush it if he changes his mind later.
Just check the darn renewals...