Rachel Keller is an American actress. She had her career beginnings in the 2010s where she first appeared in short films. In 2014, she made her film debut in Hollidaysburg. The following year, she also had her first TV appearance in an episode of The Mentalist. She later guest-starred in Supernatural. Her first notable role on the small screen was as Simone Gerhardt in the FX series Fargo. She gained wider recognition for her role as Sydney “Syd” Barrett in Legion, which she started playing in 2017. Later, she starred in the 2018 movie Write When You Get Work. She also currently stars as Cassandra in the new Netflix series The Society.