Billie Paul Piper (born Lianne Paul Piper on 22 September 1982) is an English singer and actress.

She began her career as a pop singer when she was a teenager but is now best known for portraying Rose Tyler, companion to the Doctor in the television series Doctor Who from 2005 to 2006, a role she reprised in 2008. In 2007, Broadcast magazine listed Piper at #6 in its "Hot 100" list of influential on-screen performers, the top woman on the list. She has also portrayed the prostitute Belle de Jour in Secret Diary of a Call Girl.

Piper was first educated at Brookfield School in Swindon, then moved up to Bradon Forest Secondary School in Purton, near Swindon before moving to be educated at the Sylvia Young Theatre School in Marylebone, London. Here she first met Lee Ryan, Tom Fletcher of band McFly, Matt Willis (then known as Matt Jay) of former band Busted, Jodi Albert, and Amy Winehouse.