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

She began her career in the late 1990s as a pop singer, then switched to acting. Her best-known role is Rose Tyler, the Doctor's companion in the television series Doctor Who from 2005 to 2006, which she reprised in 2008 and 2010. In 2007, Broadcast magazine ranked Piper 6th in its "Hot 100" list of influential on-screen performers; she was the highest-ranked woman on the list. From 2007 she appeared as the high-flying escort Belle de Jour in the television series Secret Diary of a Call Girl.