Zhang Yan 張燕 was a military leader during the late Eastern Han period 東漢 (25-220 CE).
He hailed from Zhending 真定 (near modern Shijiazhuang 石家莊, Hebei), and his original family name was Chu 褚, but he changed this name to Zhang as a quasi-heir of a leader of an army of the Yellow Turban rebellion 黃巾起義. Chu Yan himself joined the rebellion and assembled a division of a considerable size, and he liaised them with those of the rebel leader Zhang Niujiao 張牛角.
When the latter died he took over the whole corps and adopted the late commander's family name. Admired as a leader who was skilled in the use of the halberd, he was also called "Flying swallow" (Feiyan 飛燕). Zhang Yan was able to build up a huge army that was created by joining the troops of the various rebel leaders in many commanderies in northern China. This army was called "Army of the Black Mountain" (heishan jun 黑山軍). Yet not soon afterwards Zhang Yan laid down weapons and accepted the suzerainty of the Han dynasty. He was pardoned and given the title of Commandant pacifying troube (pingnan zhonglang jiang 平難中郎將).
As a military officer he then took part in the fights against the warlords that dominated the north China plain. He took side with Gongsun Zan 公孫瓚 against Yuan Shao 袁紹, and finally became a military leader under Cao Cao 曹操 who made him General pacifying the north (pingbei jiangjun 平北將軍).