Nicholas Kao Se Tseien O.C.S.O. (traditional Chinese: 高師謙; simplified Chinese: 高师谦; pinyin: Gāo Shīqiān; Jyutping: Gou1 Si1him1; 15 January 1897 – 11 December 2007), was a Chinese Trappist priest living in Hong Kong who had been the oldest living Catholic priest and also the oldest person ever to have had a cataract operation according to the Guinness Book of World Records.