Ko Kwat Tiong Sia (1896–1970), known as Mr. Ko Kwat Tiong and later Mohamad Saleh, was a prominent Indonesian politician, lawyer, civil servant and university lecturer. He was elected to the Volksraad (the colonial legislature) in 1935 as a representative of the Partai Tionghoa Indonesia (PTI: the 'Chinese-Indonesian Party'), and – after Independence in 1945 – headed the (the ‘Public Trustee Office’) in Central Java until retiring in 1960.