Final answer:
In the 1950s, Hollywood was significantly impacted by HUAC investigations which led to the blacklist of around 500 industry members over alleged Communist ties. The events during this period are a notable part of Hollywood's complex history with political and social issues. Thurgood Marshall was known as 'Mr. Civil Rights' for his role as an NAACP lawyer.
Step-by-step explanation:
The individuals in Hollywood who were known for their actions during the 1950s were the members of the Hollywood film industry that were investigated for Communist affiliations.
Amidst the backdrop of the Cold War and fears of subversion, the House Un-American Activities Committee (HUAC) issued 43 subpoenas to Hollywood figures suspected of promoting Communist propaganda.
Among those, ten were deemed 'unfriendly' when they refused to cooperate with the committee.
These ten individuals became known as the Hollywood Ten, and their refusal to answer questions led to prison sentences.
The outcome of the hearings was significant as it resulted in a blacklist established by Hollywood executives, thereby ending or severely hindering approximately 500 careers of those with alleged Communist backgrounds, impacting actors, writers, and directors.
NAACP lawyer dubbed 'Mr. Civil Rights'
The NAACP lawyer known as 'Mr. Civil Rights' was Thurgood Marshall (Option D). He was a prominent figure in fighting for the rights of African Americans and would later become a Justice of the Supreme Court of the United States.