King Tai of Zhou (Chinese: 周太王; pinyin: Zhōu Tài Wáng; literally: "Great King of Zhou") or Gugong Danfu (Chinese: 古公亶父; pinyin: Gǔgōng Dǎnfù; literally: "Old Duke Danfu") was a great leader of the Zhou clan during the Shang dynasty. His great-grandson Fa would later conquer the Shang and establish the Zhou dynasty.
"King Tai" was a posthumous name bestowed upon him by his descendants. He was never a king during his lifetime. He was earlier known as Old Duke Danfu (Gugong Danfu), for instance, in the Classic of Poetry. Occasionally, a few scholars refer to him as Ji Danfu, referencing his surname Ji (姬).
In the family hymns recorded in the Classic of Poetry, the Ji family is traced from the miraculous birth of the Xia dynasty culture hero and court official Houji caused by his mother's stepping into a footprint left by the supreme god Shangdi. The Records of the Grand Historian instead make Houji the son of the Emperor Ku, connecting his family to the Yellow Emperor who was sometimes also given the Zhou's surname.