Thanks Jim, I think anyone can still use the original black terror character, however, no one can now use the black terror as a trademark to sell there black terror products. Only bill black can do that now.
Once the trademark expires, if he chooses not to renew it, and he can renew it (or his company) forever now. Then that is his option. The copyright on the new black terror comics will go through the copyright cycle and be protected for i guess 95 years...
is that about right?
No. That doesn't resemble the law at all.
First, the trademark is ONLY a "mark in trade," a brand. Anybody can use public domain content regardless of trademarks, but you can't infringe on a brand because that's a fraudulent act. For example, if I advertise that my comic book features "Superman"--even if it's not the DC character--DC can sue me for misleading the consumer into thinking my comic is related to theirs.
However, as long as it's not part of the "trade dress" (anything used for marketing and advertising), I actually CAN have a character named "Superman," and there's nothing DC can do to stop me.
With me so far?
Now, here's where it gets weird. There are two kinds of trademarks, registered trademarks and (no adjective) trademarks.
A registered trademark needs to be (duh) filed with and approved by the Trademark Office (in the United States, a division of the Patent Office). It has a term length, after which it expires and can be renewed. That's the circled-R symbol.
An unregistered trademark is just an identifying feature of your work, which consumers identify with you. "Steve Rogers" is a trademark of Marvel Comics, though not registered. These trademarks operate as long as they're being used, which is why Marvel brings back the Captain Marvel trademark every few years whether anybody cares about the character or not.
And both trademarks are considered "abandoned" when there's market confusion, which is why you so often hear about Disney suing small bakeries or painters. If they sue, say, a pornographer selling "Minnie Makes Minneapolis," Disney loses the case if the defendant can find examples where other people were allowed to sell unauthorized Minnie Mouse products, because they haven't protected their trademark.
In the Black Terror case, I don't know (or, honestly, much care) if Bill Black HAD a Black Terror trademark. But unless it's active and he's been the only source for Black Terror content, then anybody could trademark the name (even registering it) and do what they want with it instead, in terms of their "trade dress."
Notice, by the way, that the trademark has nothing to do with the character itself or the stories told, and doesn't affect the use of the trademark anywhere other than the "public face" of the work.