Trương Vĩnh Ký (Chinese characters 張永記), known as Pétrus Ky and Jean-Baptiste Pétrus, (Vĩnh Long Province, 6 December 1837 - 1 September 1898) was a Vietnamese scholar whose publications helped improve understanding between colonial Vietnam and Europe. His works helped popularize the romanized script of the Vietnamese language, Quốc Ngữ, leading to its officialization in the early 20th century. He served in the French colonial regime as a linguist, and also translated many literary works into modern Vietnamese.