Billie Paul Piper (born Lianne Piper, 22 September 1982, in Swindon, Wiltshire) is an English singer and actress.

She began her career in the late 1990s as a pop singer and then switched to acting. Her most famous role is as Rose Tyler, companion to the Doctor in the television series Doctor Who from 2005 to 2006, a role she reprised in 2008 and 2010. In 2007, Broadcast magazine listed Piper at no. 6 in its "Hot 100" list of influential on-screen performers, the top woman on the list. Since 2007 she has starred as the high-flying escort Belle de Jour in the TV series Secret Diary of a Call Girl.