Film and television

Walker landed the title role in the television series Lorna Doone before making her feature debut in Journey of Honor (1991). In that same year she appeared in Les Equilibristes and in Mike Newell's Enchanted April, in which she played an aristocrat eager to escape the attentions of her persistent male admirers.^[4] Walker first gained international attention in 1992 as a single-minded English member of an Irish terrorist group in Phillip Noyce's Patriot Games.

She appeared in Douglas McGrath's 1996 adaption of Jane Austen's Emma as Jane Fairfax, the titular character's rival.^[5]

In 2003 she had a starring role in the BBC drama series State of Play.^[6]

Between 2005 and 2007, Walker played Atia of the Julii in both seasons of the HBO–BBC2 television series Rome. Her performance earned her a Golden Globe nomination in 2006 for Best Performance by an Actress in a Television Series – Drama.^[7][8]

She next played the sinister Catherine Braithwaite in "Deus Ex Machina", a two-episode story of the BBC television "cold case" crime series Waking the Dead, which also aired in January 2007. In May 2007, she appeared as Lady Bess Sedgwick in ITV's Marple: At Bertram's Hotel,^[9] and then played sugar heiress Ellis Samuels in the CBS television drama Cane, which premiered 25 September 2007.^[10]

In May 2008, Walker was cast as Sister Clarice Willow, headmistress of a private religious school, in Syfy's Battlestar Galactica prequel series Caprica.^[11] She appeared in Louis Leterrier's 2010 action fantasy remake, Clash of the Titans as Cassiopeia.^[12]

In 2011 she guest starred as Ranna Seneschal, leader of the underground city of Praxis, on the Candian sci-fy fantasy show Sanctuary.

Walker starred in BBC's crime drama Prisoners' Wives as crime wife Francesca Miller from 2012 to 2013.^[13] She went on to appear in Andrew Staunton's 2012 science fiction action-adventure film John Carter as Sarkoja, a merciless Thark.^[14]

In 2014, she had a recurring role as the character Delphine Day in the ITV series Mr Selfridge.^[15]

In 2018, Walker starred as Bel, the leading character in Age Before Beauty.^[3] From 2019 to 2022, she portrayed dominatrix Margaret "Peggy" Skyes the action crime drama show Pennyworth.^[16]

In 2020, she appeared as Lady Lunete, the Queen Regent and mother to Uther Pendragon, a recurring character for 5 episodes in the Netflix series, Cursed.^[2] Since December 2020, Walker has starred in the Netflix series Bridgerton as Lady Portia Featherington. She earned a Screen Actors Guild Award nomination in 2021 with the series cast for Outstanding Performance by an Ensemble in a Drama Series.^[17][18]

Film

Television

Theatre

Audio dramas

Video games