In China, after the death of Mao, 4 Maoist party members rose to prominence in opposition to Hua Guofeng's leadership. They wanted to preserve the Cultural Revolution and purge the "capitalist roaders" that included figures like Deng Xiaoping, Zhao Ziyang, and Ye Jianying. They were later persecuted and jailed by the Chinese leadership in 1981.
Yes, there was another official "Gang of Four" during the Cultural Revolution that presided over its enactment, but for simplicity, only the post-Mao Gang will be included.