Lee Si-a (; born July 10, 1990), birth name Lee Ji-a, is a South Korean actress and singer. She made her entertainment debut in 2011 as a member of the K-pop girl group CHI CHI. When Chi Chi disbanded in 2013, Lee turned to acting, and has appeared in television series such as More Than a Maid (2015), Signal (2016), and The Unusual Family (2016).