Wèi Yán 魏延 (?–234), courtesy name Wéncháng (文長), was a distinguished officer of Shu.

The novel Romance of the Three Kingdoms suggested that Wei Yan originally served as a mid-ranked military officer of Liu Biao, but the history books didn't officially recognize that.

He joined Liu Bei's army after Liu captured Changsha in about 209. His talent helped him to be a major general of Liu's Army in very few years. Liu offered him the place of chief executive at Hanzhong (漢中) in 219, made him be the sixth most important military man of the kingdom after the Five Tiger Generals.

After Liu's death in 223, Zhuge Liang employed him for the war with Wei. He had suggested some radical plans in order to win the war but Zhuge Liang rejected them.

When Zhuge Liang died in 234, some officers under him (including Jiang Wei) killed Wei Yan, in the title of "rebellion".

Both the history and the novel suggested that Wei intended to attack Sima Yi, the general of Wei, but people including Jiang objected to the plan and ordered Wei to retreat. Wei refused and thus attempted to kill those officers by burning down the wooden walkway and preventing them from returning to Shu. Those officers thus claimed him "rebelling" and killed him with a plot.

In the novel, Zhuge Liang had foreseen Wei Yan's revolt before his death, and secretly left instructions to be carried out to deal with it when it came. When Wei Yan rebelled, Ma Dai pretended to join him, and earned his trust, so that later, following Zhuge's instructions, he was able to strike down Wei Yan from behind without the latter suspecting.

Some people believe that Wei was an aggressive person, which is incompetent to Zhuge Liang. Moreover, Wei Yan's personality made Zhuge's followers fear him and finally decide to get rid of him. He was killed by Ma Dai