Cui Zhu 崔杼 (died 546 BCE), also called Cuizi 崔子, was a high minister in the state of Qi 齊 during the Spring and Autumn period 春秋 (770-5th cent. BCE). He was the son of Cui Wuzi 崔武子 (Viscount Wu of Cui 崔武子) and served the dukes Zhuang 齊莊公 (r. 553-548) and Jing 齊景公 (r. 547-490) as counsellor to the right.
Cui Zhu first participated in government affairs in 574 under Duke Ling 齊靈公 (r. 581-554). The latter planned to get rid of his heir apparent Prince Guang 光 and to replace him with Prince Ya 牙. He ordered Gao Hou 高厚 and Su Sha 夙沙 to protect the new heir apparent. Yet when the duke died, Cui Zhu supported Prince Guang, arrested Prince Ya and killed Gao Hou. He was therefore rewarded by Prince Guang (Duke Zhuang) with the highest state office of Counsellor to the Right.
Cui Zhu's downfall began with his marriage with Tang Jiang 棠姜, sister of Dongguo Yan 東郭偃 and widow of the duke of the small fief of Tang 棠 (near modern Liaocheng 聊城, Shandong). Duke Zhuang was stunned by her beauty and began a secret affair with Lady Jiang. Cui Zhu found out about this affair and had the Duke arrested in his own mansion, yet the duke was killed by retainers of Cui Zhu when he tried to escape. Cui Zhu then enthroned a younger brother of him, Duke Jing. A collaborator in the murder of Duke Zhuang, Qing Feng 慶封, was given the office of Counsellor to the Left.
A long conflict arose between Cui and the court historiographers of Qi who persistently recorded that Cui Zhu had killed the duke. Qing Feng finally took action and had the whole family Cui wiped out. Cui Zhu himself committed suicide.