Dai Yuan 戴淵 (271-322), courtesy name Ruosi 若思, was a general of the Eastern Jin period 東晉 (317-420). He hailed from Guangling 廣陵 (near present-day Yangzhou 揚州, Jiangsu) and in his younger years he lived as a "robber-knight" (youxia 游俠). When he learnt that the wealthy philosopher Lu Ji 陸機 (261-303) was travelling to the capital Luoyang 洛陽 (today in Henan), Dai planned to rob him, but Lu Jin, who recognized that Dai Yuan was a in fact a competent person, convinced him to begin a new life, and recommended him to Sima Lun 司馬倫 (249-301), the Prince of Zhao 趙, who used his talents and then transferred him to the service of Sima Yue 司馬越 (d. 311), Prince of Donghai 東海, as *libationer-advisor of the army (junzi jijiu 軍諮祭酒, i.e. junshi jijiu 軍師祭酒).
Dai was then appointed governor (taishou 太守) of the commandery of Yuzhang 豫章, received the nobility title of Marquis of Moling 秣陵侯, and then returned to the central government as Secretarial Censor (zhi shushi yushi 治書侍御史) and Cavalier attendant-in-ordinary (sanji changshi 散騎侍郎).
After the foundation of the Eastern Jin, he served in the Imperial Secretariat (shangshusheng 尚書省). In 321 the was given the title General conquering the west (zhengxi jiangjun 征西將軍), which gave him the command over the armies of six provinces. He was ordered to take precautions against the generals Wang Dun 王敦 (266-324) and Zu Ti 祖逖 (266-321). In 322, Wang Dun turned against the dynasty and attacked the capital Jiankang 建康 (today's Nanjing 南京, Jiangsu). The emperor gave Dai Yuan the title of General of cavalry (piaoji jiangjun 驃騎將軍), a function in which he engaged the rebels in the suburbs at Shitoucheng 石頭, but lost the battle and died.
Dai Yuan's posthumous title is Marquis Jian 簡侯 "The Simple".