At its height in the late 40s and early 50s, the Hollywood Blacklist attacked the lives and careers of people involved in Motion Pictures who had anything to do with the Communist Party, progressive political causes deemed related to communism, and refusal to assist investigations into the Communist Party. The government used two weapons: jail and economic boycott.
1947 The House Committee of Un-American Activities (HUAC) (created 1938 but preceeded by several Committees with different names which did the same work--as HUAC was succeeded by upon its disbanding) investigated 10 Hollywood workers, who refused to give testimony. The 10 were charged with "contempt of Congress" and the next day the 10 were fired. 1950 a list of 151 Hollywood professionals were named and most were barred from employment.
The Hollywood 10
Alvah Bessie, screenwriter
Herbert Biberman, screenwriter and director
Lester Cole, screenwriter
Edward Dmytryk, director
Ring Lardner Jr., screenwriter
John Howard Lawson, screenwriter
Albert Maltz, screenwriter
Samuel Ornitz, screenwriter
Adrian Scott, producer and screenwriter
Dalton Trumbo, screenwriter