Kong is most notable as the surname of Confucius and his descendants, whose family tree is the world's longest, covering over 2,500 years and more than 80 generations, in two million entries as of 2009.

The character for the Kong surname was derived from the Zi (子) family name.

[5] It first appeared during the Zhou dynasty as the courtesy name Kongfu (孔父) of a noble in the State of Song named Jia (嘉), said to be a descendant of the Tang of Shang.

Kongfu Jia was murdered, and his son escaped to the State of Lu where he adopted Kong as the name of his clan.

For example, in the State of Zheng, two of Duke Mu of Zheng's (鄭穆公) sons (surname Ji) (姬), had Shikong (士孔) and Zikong (子孔) as their respective courtesy names, and their descendants took Kong as their surname.