Registered trademarks In the US expire from any of:
1) Non-defense
2) end of term without renewal
3) explicit release
4) judicial order terminating it.
One cannot register a trademark if it's too similar to an existing one.
A registered trademark trumps an unregistered one (usually)...
The logic goes this way: Evil hat is in the same industry. So, to be allowed, it must be expired. (most TSR trademarks are.)