Bio from Wikipedia:
Louisa Rose Allen (born 29 April 1989), known as Foxes, is an English singer and songwriter originally from Southampton and now based in London.
Allen had success with her vocal work on Zedd's song "Clarity", which has so far peaked at number 8 on the Billboard Hot 100 and peaked at number one of the US Hot Dance Club Songs. She has released a single and an EP as 'Foxes', working with Sam Dixon, and has been working on her debut album. Both tracks from debut single "Youth" were featured in Gossip Girl. She also worked with Fall Out Boy on the song "Just One Yesterday". Foxes is working on her debut album to be released at the beginning of 2014 by RCA. She say the album has a "dark streak… as well as a pop element that runs through it."