Cai Hesen (March 30, 1895 – August 4, 1931) was an early leader of the Chinese Communist Party (CCP), and a friend and comrade of Mao Zedong. Cai was born in Shanghai but grew up in Shuangfeng County in Hunan Province of China. He helped Mao organize the Changsha New People's Study Society. In 1919 he went to France on the Work-Study program, and his letters of advocacy were important in convincing Mao of the Bolshevik revolutionary approach. On his return to China, he was an important leader and organizer for the young Communist Party, spent several years in Moscow, and returned to China again in 1931. While organizing revolutionary activity in Hong Kong, he was arrested and given over to Canton authorities, who executed him in August, 1931.