Pop singer-songwriter Billie Eilish is 17 years old and the first artist born in the 2000s to hit No. 1, says CNN. Eilish is also the youngest woman to reach No. 1 since 2009 when Demi Lovato debuted with "Here We Go Again" at 16. Eilish started her performing career as a dancer but had to stop after she strained her growth plate. She told the BBC that she still hopes to slowly get back into dancing. Eilish was born in L.A. on December 18, 2001 in Los Angeles.