Hayley Elizabeth Atwell (born 5 April 1982) is an English and American actress. After appearing in various West End productions, Atwell gained popularity for her roles in period dramas, appearing in the films Brideshead Revisited (2008), The Duchess (2008) and the miniseries The Pillars of the Earth (2010); for the latter two, she was nominated for a British Independent Film Award and a Golden Globe Award, respectively. Atwell rose to prominence with her portrayal of Agent Peggy Carter in the Marvel Cinematic Universe film Captain America: The First Avenger (2011), a role she reprised in later productions such as the ABC television series Agent Carter (2015–2016). Atwell also starred in the fantasy films Cinderella (2015), Christopher Robin (2018) and Peter Rabbit 2: The Runaway (2021), and had a leading role in the action films Mission: Impossible – Dead Reckoning (2023) and Mission: Impossible – The Final Reckoning (2025). For her work on stage, Atwell has received Laurence Olivier Award nominations for her leading performances in The Pride (2013) and Rosmersholm (2020).