15 Best TV Villains In The Marvel Cinematic Universe

Appeared In: Agent Carter

Johann Fennhoff was discovered by Agent Carter, the Howling Commandos and her fellow SSR agents as a prisoner near the Red Room Academy going by the name Ivchenko. Liberated and brought back to New York City to hopefully shed light on everything Leviathan, it turned out that he was actually working for the organization.

Allied with Dottie Underwood, the doctor succeeded in brainwashing Agent Yauch and even Roger Dooley - both of whom lost their lives - stole Item 17, tested it on innocents and then brainwashed Howard Stark into unleashing the gas on the city. Fortunately, his plans were thwarted, but his impact on the MCU was far from over.

Imprisoned with Arnim Zola at season's end, it was strongly implied that the seeds of their collaboration led to Bucky Barnes' brainwashing into The Winter Soldier and even, perhaps, providing the very methods which Daniel Whitehall would employ decades later.