Along with Jaclyn Smith, Doyle is the only other actor who remained with Charlie's Angels for its complete five season run.
He provided the first voice of Grandpa on "Rugrats." When he passed away, the Rugrats episode "Lady Luck" was dedicated to him.
Sometimes mistaken for actor Tom Bosley, who played Richie Cunningham's dad, Howard, in the TV series "Happy Days" (1974), because of Doyle's "Bosley" character on "Charlie's Angels" (1976), and a slight similarity in facial features, body type and voice.