Red August, originally meaning August 1966 of the Cultural Revolution, is a term used to indicate a series of massacres in Beijing which mainly took place during the period.

Subsequent to a meeting on Tiananmen Square between Mao Zedong and Song Binbin, a leader of the Red Guards, on August 18, 1966, the Red Guards started their massive killing in the city as part of the destruction of the "Four Olds" (Old Ideas, Old Culture, Old Customs, and Old Habits). During the massacres, Mao Zedong publicly opposed any government intervention to the students' movement, and Xie Fuzhi, the Minister of Ministry of Public Security, instructed police and public security agencies to protect the Red Guards instead of arresting them. However, the situation had grown out of control by the end of August 1966, forcing the Central Committee of the Chinese Communist Party (CCP) and Chinese government to take multiple interventions that gradually brought the massacre to an end.

The Red August of Beijing is regarded as the origin of Red Terror in the Chinese Cultural Revolution, instigating Red Guards' movement in a number of cities where local political leaders, intellectuals, teachers and members of the Five Black Categories were persecuted and even killed by the Red Guards.