Gan Eng Seng (simplified Chinese: 颜永成; traditional Chinese: 顏永成; pinyin: Yán Yǒngchéng; Pe̍h-ōe-jī: Gân Íng-sîng; 1844–1899) was a Chinese businessman and philanthropist who was one of the early pioneers of Singapore. He is known for his generosity to many charitable causes in Malaya and Singapore during the British colonial era. Some of his most recognised contributions were the setting up of Gan Eng Seng School, the Thong Chai Medical Institution, Tan Tock Seng Hospital, and the Ee Hoe Hean Club.