he doesn't have any movies, so I wouldn't know if he's "obscure" or not. that said, a single word cannot be trademarked or copyrighted. as long as your character doesn't look, think, or act like the aforementioned Vanguard, it doesn't really matter. Like Thor. I can write a norse god named Thor. I can put him in a hero team. But I CANNOT write him in the same way that Marvel did. I can't describe him as being like chris Hemsworth, I can't make him friends with a giant green monstrosity, and I can't write him fighting a giant purple alien.
All that is to basically say, as long as yours crosses to the 'different enough' side of things, it should be fine.
As for readers sending flak your way, I doubt most people would catch that, simply by the name being the same. Now, if the backstory, looks, or powerset were similar, they might notice and appreciate the reference. But that's when you start to get into copyright issues.
