Griff Barnett (born Manley Griffith, November 12, 1884 – January 12, 1958) was an American actor.

Barnett was born in Blue Ridge, Texas in 1884.

In the early 20th century, Barnett was a member of the Mack-Hillard stock theater company in Wichita, Kansas. He also worked with stock theater companies in the Chicago area.

He played the role of the Rexall family druggist in commercials on The Phil Harris-Alice Faye Show on radio in the late 1940s and early 1950s. He also appeared in numerous films from the 1930s through the 1950s, including To Each His Own (1946), Apartment for Peggy (1948), and Pinky (1949). He frequently played doctors or lawyers. In 1954, he appeared in episode 131 of the TV series, The Lone Ranger.

Barnett died of pneumonia and heart trouble at home in El Monte, California, on January 12, 1958, aged 73. He is buried in Rose Hills Memorial Park in Whittier, California.