Deng Ai (died 264) was a military general of Cao Wei during the Three Kingdoms era of Chinese history. It was said that whenever he saw a hill or wide valley, he would immediately size up the best places to store grain and position troops. His talent was recognized by Sima Yi, who recommended him to take up greater appointments. Deng Ai also defended Wei from attacks led by Jiang Wei of the rival state of Shu Han.

In 263, Deng Ai took part in the campaign against Shu with Zhong Hui. Jiang Wei fended them off somewhere south of Hanzhong. Deng Ai suggested to pass troops through Yinping (陰平) but Zhong Hui rejected the idea.

Deng Ai then carried out his own plan with his son Deng Zhong and troops and it turned out to be a great success. They eventually managed to enter Chengdu, and the Shu emperor Liu Shan surrendered.

Jiang Wei, however, did not want Shu to fall. He determined that Zhong Hui wanted to rebel against Wei. They united, defamed Deng Ai, and ordered Wei Guan to capture him. Jiang Wei's plan failed and the Wei army killed Zhong Hui and Jiang Wei. These soldiers tried to rescue Deng Ai, but Wei Guan feared that they might take vengeance on him so he killed both Deng Ai and Deng Zhong.