Gan Eng Seng (Chinese: 颜永成; Pinyin: Yan Yongcheng; 1844—1899) was one of the early Chinese pioneers of Singapore known for his generosity to many charitable causes during the era of the British Straits Settlements of Malaya and Singapore. Some of his most recognised contributions known were the setting up of Gan Eng Seng School, the Thong Chai Medical Institution, Tan Tock Seng Hospital and the Ee Hoe Hean Club.
Gan was of Hokkien Chinese descent, born and educated in Melaka, and the eldest son of five in his family. His forefathers emigrated from Fujian Province, China to Malaya. Owing to poor circumstances, he probably had an elementary school education in which he learnt to read and write in simple English and keep accounts. After his father's death, sixteen year old Gan was involved in the nutmeg business on a very small scale. Later, he was taken on as an apprentice by Messrs. Guthrie and Company. Gan was diligent and capable, and his ability won him the recognition and keen interest of Thomas Scott, one of the partners in the company. Scott was one of the early British pioneers responsible for developing Tanjung Pagar and the port of Singapore.