Atwell's debut as Peggy Carter, a British agent working with the Strategic Scientific Reserve (SSR), showcasing her strong will and romantic connection with Steve Rogers.

Atwell reprised her role in a short film, "Agent Carter", which follows Peggy's adventures after World War II, leading to the formation of S.H.I.E.L.D.

Atwell made a brief appearance as an elderly Peggy Carter in "Captain America: The Winter Soldier", showing the character's later life.

Atwell starred in the "Agent Carter" television series, which explored Peggy's post-war life as she battles new threats and navigates a male-dominated world. The show ran for two seasons.

Atwell appeared as Peggy Carter in a dream sequence experienced by Steve Rogers in "Avengers: Age of Ultron".

Atwell had a cameo as Peggy Carter in "Ant-Man", appearing in a flashback scene.

Atwell reprised her role as Peggy Carter, who Steve Rogers travels back in time to be with, altering his personal timeline and allowing him to finally have the life he always wanted.

Atwell voiced Peggy Carter/Captain Carter in the animated series "What If...?", exploring an alternate reality where Peggy takes the Super-Soldier Serum instead of Steve Rogers.

Atwell played Captain Carter in "Doctor Strange in the Multiverse of Madness", appearing as a member of the Illuminati from another universe.