Lord Xinling (Xinling Jun 信陵君, d. 243 BCE), personal name Ji Wuji 姬無忌 (also written 姬毋忌 or Ji Wangji 姬亡忌) and known under the names Wei Wuji 魏無忌, "Ducal Son" Gongsun Wuji 公子無忌 or Wei Gongzi 魏公子, was a high minister of the state of Wei 魏 during the late Warring States period 戰國 (5th cent-221 BCE).
Wuji was the youngest son of King Zhao of Wei 魏昭王 (r. 295-277). On the accession to the throne of his half-brother King Anxi 魏安釐王 (r. 276-243), he was enfeoffed as Lord Xinling.
Wuji was fond of wandering philosophers, disputers and worthies of all kinds, and assembled 3,000 of them at his court. During the Han period 漢 (206 BCE-220 CE), a 21 chapters long book Weigongzi 魏公子 was kept in the imperial library which might have been compiled by his retainers.
In 257, his used the plan of one of his counsellors, Hou Ying 侯嬰, killed general Jin Bin 晉鄙 and led his troops against the army of Qin 秦, that had invaded the state of Zhao 趙 to liberate the besieged city of Handan 邯鄲, capital of Zhao.
He stayed for ten years in Zhao before he returned to Wei, this time again to repell the armies of Qin from the territory of Wei. At the head of the joint armies of five allied states, he defeated the Qin army at Hewai 河外. But shortly after the king of Wei, envious of Wuji's powerful position, deprived him of his military power. He died soon in a disappointed state.