Sharon Duncan-Brewster (born 8 February 1976) is a British actress. She is known for her role as Crystal Gordon in Bad Girls during the first four series; her role as Trina Johnson on EastEnders; and her role as Maggie Cain in the autumn 2009 Doctor Who special, The Waters of Mars. More recently, she has played Imperial Planetologist Dr. Liet-Kynes in Denis Villeneuve's adaptation of Frank Herbert's Dune.