Katharine Juliet Ross (born January 29, 1940) is an Academy Award-nominated American film and stage actress. Trained at the San Francisco Workshop, she is perhaps best known for her role as Elaine Robinson in the 1967 film The Graduate, opposite Dustin Hoffman, and her role as Etta Place in 1969's Butch Cassidy and the Sundance Kid, opposite Paul Newman and Robert Redford. She has also established herself as an author, publishing several children's books.

Ross was born in Hollywood, California, when her father was in the Navy. Her family later settled in Walnut Creek, California, east of San Francisco. She graduated from Las Lomas High School. She has lived in Malibu, California since the late 1960s. While attending Diablo Valley College in Pleasant Hill, California she starred in a student film by Jim and Artie Mitchell (of O'Farrell Theatre fame).

In 1966, Ross appeared in the episode "To Light a Candle" of Barry Sullivan's NBC western television series The Road West.