Dottie Underwood

Dottie Underwood is a Soviet operative trained from childhood by the Leviathan program to infiltrate the United States as a sleeper agent. Posing as Peggy Carter's neighbor and later resurfacing across both seasons of Agent Carter, she remains one of the few people capable of matching Peggy in a fight — and, as of the show's cancellation, still at large.

First turns up in Agent Carter (Season 1).