- Birth name was Leian, but her parents legally changed it to Billie less than a year after she was born.
- First acting gig was on the British Saturday morning kids' show Scratchy and Co.
- Studied acting at London's Sylvia Young Theatre School, where her classmates included pop-soul singer Amy Winehouse.
- Was an extra in the big-screen musical Evita (1996), giving her the chance to act alongside her idol, Madonna.
- At the age of 15, her hit song "Because We Want To" debuted at No. 1 on the UK singles chart, making her the youngest solo artist ever to accomplish the feat.
- Earned acclaim playing sidekick Rose Tyler on the BBC's 2005 resurrection of sci-fi series Doctor Who.
- Released an album of her greatest hits, titled Billie: The Singles Collection, in 2012.