The Masters of Evil are the traditional arch-nemeses of the Avengers, having appeared in at least seven different incarnations over the years. Over 60 super-villains have operated as members of the Masters, under the command of both Baron Zemos, Ultron, Egghead, Doctor Octopus, the Crimson Cowl, and Max Fury.
The Enchantress worked with Baron Heinrich Zemo in the original Masters of Evil.
The Black Knight was briefly a member of the second Masters, when Ultron led them disguised as the Crimson Cowl.
Dragonfly and Constrictor were members of the sixth Masters, led by a new female Crimson Cowl.
Arcade, Madcap, Taskmaster, Moses Magnum, Griffin and Pink Pearl were members of the seventh Masters, led by Max Fury and the Shadow Council. Now under the control of Baron Helmut Zemo, the roster has expanded to include Hellstorm, Constrictor, Mudbug, and Snot.