Lucy Alexis Liu (born December 2, 1968) is an American actress. Her accolades include winning a Critics' Choice Television Award, two Screen Actors Guild Awards and a Seoul International Drama Award, in addition to nominations for a Primetime Emmy Award.

Liu has starred as Ling Woo in the television series Ally McBeal (1998–2002), Alex Munday in two Charlie's Angels films (2000 and 2003) and Joan Watson in the crime-drama series Elementary (2012–2019). Her film work includes starring in Payback (1999), Shanghai Noon (2000), Chicago (2002), Kill Bill: Volume 1 (2003), Lucky Number Slevin (2006), Watching the Detectives (2007), The Man with the Iron Fists (2012), and Set It Up (2018).

Liu provided voice acting for Master Viper in the Kung Fu Panda franchise (2008–2016) and Silvermist in the Tinker Bell series (2008–2014). Her other voice credits include Maya & Miguel (2004–2007), Mulan II (2004), as well as the English and Mandarin-dubbed versions of Magic Wonderland (2014) and The Tale of the Princess Kaguya (2013). Most recently, she has voiced Callisto Mal in the Disney-animated film Strange World (2022).