There are lots of possible maf roles:
Magneto
Apocalypse
DocOc (although he could possibly be an indie role too)
Carnage
Venom
Loki
Hela
Green Goblin
But that´s only a few ones I know about, those verses are huge! Plus I´m not the biggest marvel nerd, so I never know which ones are Marvel and which ones are DC xD
loki and hela is mcu only. It should be the baddies from the x-men movies (magneto, apocalypse, sebastian shaw, mystique(
), fantastic four (dr.doom, silver surfer), spiderman movies (green goblin, doc ock, venom, sandman, lizard, electro), and baddies from other movies (like blade, ghost rider)
some of the ones listed above started out as bad guys then became good so not sure how they would fit