Elizabeth Mitchell (born Elizabeth Joanna Robertson: March 27, 1970) is an American actress. She is known for her lead role as Dr. Juliet Burke on the ABC drama mystery series Lost (2006–2010). Mitchell also had lead roles on the television series V (2009–2010), Revolution (2012–14), and Dead of Summer (2016), as well as a recurring role as the Snow Queen on Once Upon a Time (2014). She has starred in such films as Gia (1998), Frequency (2000), The Santa Clause 2 (2002), The Santa Clause 3: The Escape Clause (2006), and The Purge: Election Year (2016).