Mia Sinclair Jenness (born December 14, 2005) is an American teen theater actress. She was one of three girls who rotated as the star title character on the US tour for Matilda the Musical. In the off-Broadway play Mary Page Marlowe, she portrays the 12-year-old version of Mary. In 2018, she voiced the title character Nancy Clancy on Disney Junior's animated television series Fancy Nancy. She also had an ensemble and understudy role on the 2014–15 Broadway production of Les Miserables. She portrayed Lily Nill in the pilot episode for the TV series Panic. She voices young Powder in the Netflix League of Legends-based series Arcane.