Short answers, pulled from the story.
The Screen Actors Guild was founded in 1933. A meeting in March 1933 of six actors, including Ralph Morgan, Kenneth Thomson, and Alden Gay, led to the Guild's formation, with Ralph Morgan serving as its first president.
SAG was created in 1933 to eliminate the exploitation of Hollywood actors, who were being forced into oppressive multi-year contracts with major studios. Those contracts gave studios the right to dictate performers' public and private lives, contained automatic renewal clauses, and included no restrictions on work hours or minimum rest periods.
SAG membership voted to merge with the American Federation of Television and Radio Artists on the 30th of March 2012, creating SAG-AFTRA. At the time of the merger, the two unions already shared 44,000 dual members.
Ronald Reagan served as president of the Screen Actors Guild for two terms: 1947-1952 and 1959-1960. During the HUAC hearings, he was also known to the FBI as Confidential Informant T-10 and testified before the committee without publicly naming names.
Kathleen Nolan became the Screen Actors Guild's first female president in 1975. She led the Women and Minorities Rally on the 10th of October 1979 and served through 1979.
The Screen Actors Guild Awards were established in 1995 and became recognized as a significant indicator of success at the Academy Awards. The awards continued after the 2012 merger under SAG-AFTRA.