Walter Stacy Keach Jr. (born June 2, 1941) is an American actor, active in theatre, film and television since the 1960s. Keach first distinguished himself in Off-Broadway productions and remains a prominent figure in American theatre across his career, particularly as a noted Shakespearean. He is the recipient of several theatrical accolades: four Drama Desk Awards, two Helen Hayes Awards and two Obie Awards for Distinguished Performance by an Actor. He was nominated for a Tony Award for Best Actor in a Play for his performance in Arthur Kopit's 1969 production of Indians.

In film, he garnered critical acclaim for his portrayal of a washed-up boxer in the John Huston film Fat City (1972) and appeared as Sergeant Stedenko in Cheech & Chong's films Up in Smoke (1978) and Nice Dreams (1981).[4] His other notable film credits include Brewster McCloud (1970), Doc (1971), The Life and Times of Judge Roy Bean (1972), The New Centurions (1972), Luther (1974), Slave of the Cannibal God (1978), The Ninth Configuration (1980), The Long Riders (1980), Roadgames (1981), Batman: Mask of the Phantasm (1993), Escape from L.A. (1996), American History X (1998), The Bourne Legacy (2012) and Nebraska (2013).