The Masters of Evil is a supervillain team who fought the Avengers.
The team decided to steal a shipment of highly dangerous government weapons. They came across the Avengers who were joined by their former teammate Captain America.
In the comics
It was originally formed by Baron Heinrich Zemo, father of the one featured in the series, Baron Helmut Zemo.
The team is often considered the arch-enemies of the Avengers along with Ultron and Kang.
Has been led by both Baron Zemos, Ultron, Egghead, Doctor Octopus, and Justin Hammer.
Other members have included Beetle, Grey Gargoyle, Hydro-Man, Klaw, Scorpion, Shocker, and Wonder Man.