and Carnage. and Juggernaut (sometimes anyway, sometimes it's just brown)
and on the hero side of things, there is Volstagg, and Hellstrom,and Dum Dum Dugan, and D-Man, and Hyperion.
I know some of those are not exactly household names, but...
I think a lot of it is that in early comics, black hair was by far the most common, because printing and colouring was... limited. An those colours have stuck. I mean, just think of how many characters have black hair, despite it not actually being a very common colour on caucasian men in real life. It was just the easiest thing to draw/colour.