Holliday Clark Grainger, also credited as Holly Grainger, is an English screen and stage actress. Some of her prominent roles are Kate Beckett in the BAFTA award-winning children's series Roger and the Rottentrolls, Lucrezia Borgia in the Showtime series The Borgias, Robin Ellacott in Strike, DI Rachel Carey in the BBC One crime drama The Capture and Estella in Mike Newell's adaptation of Great Expectations.
Her first experience of acting was at age five when she was scouted for a BBC TV series. She appeared in many TV shows and independent films as a child actor.
In May 2021, she gave birth to twins with her partner Harry Treadaway.