The Screen Actors Guild is one of Hollywood's most powerful, and at times fractious, organizations.
Considered Hollywood's largest union, it was founded in 1933 when veteran character actor Ralph Morgan and other actors rebelled against an exploitative studio system.
The notoriously divided guild has a colorful history of infighting. SAG members still debate whether one-time guild president Ronald Reagan and his allies shortchanged members when the union accepted a compromise from the studios that would pay residuals only for movies made after Jan. 31, 1960.
More recently, the union has fought labor battles over the amount actors should receive from digital productions.
On its website, SAG describes its beginnings this way: "Both idealism and outrage motivated the Founding Fathers and Mothers who created the Screen Actors Guild. Idealism, in that they believed they could succeed in doing, as Guild President Ralph Morgan once said, "the greatest good for the greatest number" by building a respected organization to protect actors. And outrage primarily over long, grueling hours and workweeks that they found intolerable in Hollywood."
SAG has about 120,000 members.