system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel/DC] How does superhero marking work?

For example, I was reading a Fantastic Four comic, and Reed was eating Hulk Smash cereal. It got me wondering.

Do they have to ask for permission to do things like that? If so, how do companies get certain characters to agree to it? Maybe a guy like Superman would do it, but I doubt Batman would even respond to the request. So how would they be legally able to use his likeness to sell toys or plushies? Wouldn’t they be afraid that they’d get sued

Just curious.
gpt
Well, in order to copyright/trademark a name or likeness you either need to reveal your secret identity or have the money to hire a lawyer and set up an LLC or something to hold the trademark for you. The company you have holding your trademarks would still need to pay you in some way. So there would be a money trail to follow.

So yea, if you started selling knock off Batman stuff, you could probably be sued, but that would open the hero up to the possibility of being outed.