John Rockwell was the brother of film character actor Charles Trowbridge. He was a film actor for Columbia Studios and acted in film "westerns", predominately, but also worked for 'Republic Pictures Studios' for many years. He died at Glendale Sanitarium Hospital from 'hyperstatic shock' and 'enforced bed rest'. In other words, he had a 'nervous breakdown'. He also lived in the city of Glendale, California which is a suburb of Los Angeles, California.

Granite-jawed, glowering Jack Rockwell--who also happened to be the brother of another veteran character actor, Charles Trowbridge--played more lawmen than probably any other actor in westerns. A sheriff, a marshal, a Texas Ranger . . . if you were watching any western from the 1920s to the 1940s - especially from Columbia or Republic - and somebody wearing a badge and a gun showed up on onscreen, chances are it was Jack Rockwell. A solidly built man, Rockwell's serious, no-nonsense demeanor made whatever character he was playing - mostly lawmen, but there was an occasional respite where he played a rancher, businessman, the father of the heroine, or even a villain - just that much more believable. He appeared in around 250 films in his career. Not all of his roles were lawmen, but enough of them were to ensure that western aficionados will forever identify Jack Rockwell as the man who represented the law in the West.