Ella Summer Reed Purnell (born 17 September 1996) is a British actress. She began her career as a child actress in West End theatre and films, including Never Let Me Go (2010), Intruders (2011) and Maleficent (2014). Her other films include Miss Peregrine's Home for Peculiar Children (2016), Churchill (2017) and Army of the Dead (2021).

On television, Purnell starred in the series Ordeal by Innocence (2018) and Belgravia (2020). She is known for her work in the critically acclaimed series, Yellowjackets (2021–present), Fallout (2024–present) and Sweetpea (2024–present). She voiced Jinx in Arcane (2021–2024) and Gwyndala in Star Trek: Prodigy (2021–2024).