I was looking at the filmography of Pat Flaherty (1897 - 1970) and it is impressive, especially for someone who was not much more than an extra. He managed to appear in almost 200 films in about twenty years, from 1934 to 1955. I bet some of them are your favorites.
After World War I, he started his working life as a baseball player and then a football player, and took up acting later. I suppose his military career and then his sportsmanship caused him to be cast many times as a cop or prison guard, or as a baseball player or umpire. I counted three roles as an umpire, three as a manager, and at least one each as a baseball player, polo player and hockey player; plus more than 45 roles as a cop or guard; and many more as a detective, deputy or whatever!
The Thin Man (1934), Bright Eyes (1934) with Shirley Temple, Mutiny on the Bounty (1935) with Charles Laughton, My Man Godfrey (1936), A Star is Born (1937) with Janet Gaynor, His Girl Friday (1940), The Grapes of Wrath (1940), The Great Dictator (1940) with Charles Chaplin, Meet John Doe (1941), Yankee Doodle Dandy (1942), The Treasure of the Sierra Madre (1948) where he played the bar patron who warns Curtin and Dobbs about McCormick, The Asphalt Jungle (1950), and Pat and Mike (1952). What a list!
Flaherty was also a technical advisor on sports films, and is credited with teaching Gary Cooper how to pitch in The Pride of the Yankees in 1942, and was advisor for The Babe Ruth Story in 1948. Pretty impressive for an actor who was uncredited in 155 of his 199 roles!