Final answer:
Joseph McCarthy was a Wisconsin Senator who used fear and intimidation tactics to heighten the Red Scare during the Cold War. He made unsupported accusations of Communist infiltration without providing any evidence.
Step-by-step explanation:
Joseph McCarthy was a Wisconsin Senator who rose to prominence during the Cold War in the United States. He heightened the Red Scare by making unsupported accusations of Communist infiltration in the government and other institutions. McCarthy used fear and intimidation tactics, making claims of having lists of Communists without providing any evidence. His actions created a climate of suspicion and paranoia, leading to the blacklisting of many innocent individuals.