Marsha Thomason (born August 29, 1965) is an English television and film actress. She is best known for playing Nessa Holt in the first two seasons of the NBC series Las Vegas, Naomi Dorrit on the ABC series Lost, and FBI agent Diana Berrigan on the USA Network series W'hite Collor. She played Sara Evers and Elizabeth Henshaw in The Haunted Mansion (film).