Bi Gan or Bigan (Chinese: 比干) was a prominent Chinese figure during the Shang dynasty. He was a son of King Wen Ding, and an uncle of the last Shang king, Di Xin. He is immortalized as a Taoist deity. Though he is commonly known as Bi Gan, his actual surname is "Zi" (子).
Notorious for his corruptness, Di Xin was annoyed by Bi Gan's advice to rectify his ways. He ordered Bi Gan's execution through extraction of the heart 比干剖心, under the eerie pretext of curiosity "whether the Sage's heart has seven openings". The plot became a popular element of the Warring States philosophic discourse.
Bi Gan was honored by Confucius as "one of the three men of virtue" of the Shang, together with Weizi and Jizi 箕子 (The Analects, Wei Zi chapter).
Bi Gan was later deified as Cai Shen, the god of fortune. It was greatly popularized by depiction in the famous Ming dynasty novel The Investiture of the Gods, describing his confrontation with Daji.