Tsay Ting-kuei (Chinese: 蔡丁貴; Pe̍h-ōe-jī: Chhòa Teng-kùi; born 24 March 1949) is a Taiwanese civil engineering professor, political activist, and former government official.

A professor at National Taiwan University in Taipei, he has conducted research in areas including coastal engineering and computational hydraulics.

In politics, he served in various positions in the Chen Shui-bian administration in the mid-2000s, and rose to greater prominence for his protests in support of the Taiwan independence movement.

[2] In October 2008, Tsay led the Taiwan Association of University Professors in a hunger strike outside the Legislative Yuan building in support of relaxation of the procedures for public referendums.

[7] In 2012, Tsay and the TRA also initiated a walking protest in support of clemency for former president Chen Shui-bian, who had been imprisoned after a conviction for corruption charges.