Timothy David "Tim" Donnelly is an American actor and director, and is the younger brother of Jack Webb's stock director Dennis Donnelly. He had several different supporting roles in episodes of late '60s and early '70s Webb-produced shows, such as Dragnet 1967-1970 and Adam-12. In late-1971, Jack Webb personally selected Donnelly for the role that made him famous, that of the wisecracking Firefighter Chester B. "Chet" Kelly, in the Mark VII television series Emergency! After "Emergency!'s" cancellation in 1978, Donnelly appeared in several other series outside of those by Mark VII. He starred in episodes of television series such as Vega$, Hawaii Five-O, The Virginian, B. J. and the Bear, Enos and The A-Team, and even had starring roles in films such as The Clonus Horror and The Toolbox Murders. He also had an uncredited role as a 13-year-old Baby Face Nelson, in the 1957 movie of the same name. He left acting in 1984, but has appeared at various Emergency! conventions. 

September 3rd, 1944 in Los Angeles  /  Died:   Sep 19th, 2021 - aged 77