In the 1940s and 1950s, the United States was in the grips of a "red scare." Many prominent individuals suspected of sympathizing with liberal or humanitarian causes were branded a communist threat, and even accused of espionage. Hollywood was a major focus of the accusations, and after 10 actors refused to testify in front of the House Committee on Un-American Activities, the blacklist was created. Hundreds of actors, actresses, directors, screenwriters and other entertainment professionals were barred from working. Here are some of the famous people who were on the Hollywood blacklist.