Ke Zhao or Chao Ko (Chinese: 柯召; pinyin: Kē Zhào; Wade–Giles: K'o Chao, April 12, 1910 – November 8, 2002) was a Chinese mathematician born in Wenling, Taizhou, Zhejiang, People's Republic of China.
Zhao graduated from Tsinghua University in 1933 and obtained his doctorate from the University of Manchester under Louis Mordell in 1937. His main fields of study were algebra, number theory and combinatorics. Some of his major contributions included his work on quadratic forms, the Erdős–Ko–Rado theorem and his breakthrough on Catalan's conjecture. He was later a professor at Sichuan University and became the president of the university.