Lily Chloe Ninette James (née Thomson; born 5 April 1989) is an English actress. She studied acting at the Guildhall School of Music and Drama in London and soon began her acting career in the British television series Just William (2010). Following a supporting role in the period drama series Downton Abbey (2012–2015), James had her film breakthrough by playing the eponymous role in the fantasy film Cinderella (2015).

James went on to play Natasha Rostova in the television series War & Peace (2016), and in 2017, she starred in two critically and commercially successful films"the action film Baby Driver and the war drama Darkest Hour. She played the younger version of Meryl Streep's character in the musical film Mamma Mia! Here We Go Again (2018).