Super-Team Family: The Lost Issues! has been posting covers of fantasy match-ups featuring inter-company crossovers the likes I used to dream about when I was a wee lad. (And probably would nowadays if I had the time!)
Here's a rather cool cover featuring the Thing squaring off against Black Adam. Black Adam (before the nu52 era of books) seemed to be positioned as the Sub-Mariner of the DC Universe with his "is he a hero or is he a villain?" status. Plus the fact that he's dressed in black and yellow, is often seen sporting pointed ears, and seems to go to the same barber as Namor helped to visually cement that impression.