From Wikipedia

Guinn Terrell Williams Jr. (April 26, 1899 – June 6, 1962) was an American actor who appeared in memorable westerns such as Dodge City (1939), Santa Fe Trail (1940), and The Comancheros (1961). He was nicknamed "Big Boy" as he was 6' 2" and had a muscular build from years of working on ranches and playing semi-pro and professional baseball.

Williams made his screen debut in the 1919 comedy, Almost A Husband, with Will Rogers and Cullen Landis, and was featured in a large supporting role ten years later in Frank Borzage's Lucky Star with Janet Gaynor and Charles Farrell. Throughout the 1920s Williams would have a string of successful films, mostly westerns.

He then appeared in The Great Meadow alongside Johnny Mack Brown, which was Brown's breakout film. Throughout the 1930s, Williams acted in supporting roles, mostly in westerns, sports, or outdoor dramas. Although not the lead actor in any of them, he was always employed, and was successful as a supporting actor. He often played alongside Hoot Gibson and Harry Carey during that period. In 1941, he became one of many actors cast by Universal Pictures in their large film series, Riders of Death Valley. From the late 1930s to the mid-1940s, Williams appeared in supporting roles in a number of A-pictures, sometimes with high billing, such as You Only Live Once, and in Columbia's first Technicolour film The Desperadoes (1943).

Williams was frequently teamed with Alan Hale, Sr. as sidekicks to Errol Flynn in several of his pictures. In 1960, he was cast in the epic film The Alamo and in Home from the Hill with Robert Mitchum. His last role was opposite his close friend John Wayne and Stuart Whitman in The Comancheros.