I ran across this interesting article last year about the origins of the Screen Actors Guild (SAG) in the United States (which has merged with the American Federation of Television and Radio Artists in 2012 to form SAG-AFTRA). SAG started in 1933 to prevent the exploitation of actors by movie studios.
Among the founding members was Boris Karloff (most famous for portraying Frankenstein). Karloff was concerned about long hours (including one 25-hour stretch) and dangerous working conditions on set and one of the first SAG meetings took place in Karloff’s garage. He served as a Board member and officer of SAG from 1933 to 1951.
Bela Lugosi (most famous for playing Dracula) was also an early member. Lugosi emigrated from Hungary in the 1920s after engaging in labor activism among actors there. Both Lugosi and Karloff were SAG recruiters, soliciting memberships from actors on the sets of their movies.
-- Bob Barnetson