Originally Posted by Dark Raven
Masters of Evil would fit if he's planning to introduce Wanda and Pietro. He might be just substituting the Brotherhood for the Masters.
But if he does have the Masters, who would they be? If we simply have all the enemies from the previous Marvel movies, I'm not sure all of them could possibly work together. They'd have a harder time at it than the Avengers themselves, because they might have even bigger egos and personalities, each one wanting to be the leader.
With many of the Masters teams in the comics, you usually had one person who seemed like a leader (eg Baron Zemo) and the rest who were more lackey material or heavies. If it had been a TV series, they could've devoted an episode or two to the formation of the Masters and we could've seen things from the villains' camp.
Killian, Crossbones, Red Skull, Malekith and/or Kurse, Abomination, etc. I could see them working together, all assembled by Thanos(they don't have to know that), like Fury assembled the Avengers.