Peggy Carter (MCU)

Overview
Peggy Carter is a supporting character in the Marvel Comics to Captain America. She first appeared in Tales of Suspense #77 published in May 1966 as a retroactive implant as Captain America's lover during World War II as a daring American secret agent and also a distant relative to Sharon Carter; a modern-day S.H.I.E.L.D field agent who became romantically involved with Captain America as well.

Portrayed by Hayley Atwell in the Marvel Cinematic Universe, she is a major supporting character in the Captain America films and it was later revealed that she continued to fight against Hydra post-WW II in the Agent Carter TV series and was a major contributor along with Howard Stark in the formation of the Strategic Homeland Intervention, Enforcement, and Logistics Division or as it was later known as S.H.I.E.L.D. in the Agents of S.H.I.E.L.D. TV series.

Quotes

 * These assets are now under the protection of the Strategic Scientific Reserve. They'll be hidden out of sight, indefinitely... as will you.