Yu Yi 庾翼 (305-345), courtesy name Zhigong 稚恭, was a general and calligrapher of the Eastern Jin period 東晉 (317-420). He hailed from Yanling 鄢陵 (today in Henan) in the commandery of Yingchuan 潁川 and was a younger brother of Yu Liang 庾亮 (289–340) and Yu Bing 庾冰 (296-344). As a member of an eminent family (menfa 門閥), he obtained an excellent education and started his career in the staff of Defender-in-chief (taiwei 太尉) Tao Kan 陶侃 (259-334).
When his brother Yu Liang died, Yu Yi took over the command over the garrison of Wuchang 武昌 (Echeng 鄂城, Hubei), bearing the title of General appeasing the west (anxi jiangjun 安西將軍) and having the function of regional inspector (cishi 刺史) of the province of Jingzhou 荊州. In this position, he was in command of the armies of six provinces of central China.
In 343, Yu Yi decided – without backing by the court – to transfer the seat of his command to Xiangyang 襄陽 (today's Xiangfan 襄樊, Hubei), requisitioned carts and cattle and recruited troops within his jurisdiction, with the plan to attack with 40,000 troops the empire of Later Zhao 後趙 (319-350) which controlled the northwest. Hefty protests by the local magnates forced him to give in. Yu Yi saw the reconquest of north China as his "private duty" (ji ren 己任).
In 343, Yu Yi concluded an alliance with the empires of Former Yan 前燕 (337-370) and Former Liang 前涼 (314-376). In summer, Dai Kai 戴開, the governor of Runan 汝南 and subject of the Later Zhao empire, defected to the Jin. While Huan Xuan 桓宣 secured River Dan 丹水, Huan Wen 桓溫 (312-373) passed over to Guangling 廣陵, and He Chong 何充 (292-346) took over the defense of the Huai-Si region 淮泗 (northern part of present-day Jiangsu). Lu Yong 路永 secured Hefei 合肥. Yu's huge army met the enemy outside of Xiangyang and killed half of the 600-odd cavalry of the Zhao army. In the next summer, Huan Xuan attacked the army of Zhao general Li Huang 李皝, but he was defeated. In winter, Yu had to withdraw to Xiakou 夏口 (today part of Wuhan 武漢, Hubei).
Shortly later, Yu Yi died from an epidemic. His posthumous honorific title was Marquis Su 肅侯 "The Solemn".
Yu's contemporaries were not without reservation towards his nepotism (recommending his own sons for promotion) or the arrogance his displayed towards some court officials like Yin Hao 殷浩 (d. 356), saying that such men were only of use when the empire was at peace. He also despised the contemporary mode of intellectual and philosophical discourse, the "pure talks" of the "School of the Mystery" (xuanxue 玄學). In Yu's eyes, their chattering was without use for the world – in contrast to the thinkers of the age of antiquity. Of Yu Yi's writings, which had a total volume of 22 juan, just a few texts have survived, among them fragments of a commentary on the "Confucian Analects", Lunyu Yushi shi 論語庾氏釋, and fragments of a history of the Western Jin period 西晉 (265-316), Jin chunqiu 晉春秋.
Yu Yi was good in calligraphy and mastered chancery script (lishu 隸書) and grass script (caoshu 草書). In his own times he was so famous that he was compared with the "calligraphy god" Wang Xizhi 王羲之 (303-361). Yu Jianwu's 庾肩吾 (487-551) calligraphy critique Shupin 書品 ranked Yu Yi's works as 2A (fourth from nine categories), with "coloured sounds and surpassing strength" (sheng cai qiu yue 聲彩遒越). Li Sizhen's 李嗣真 (d. 696) Shuhoupin 書後品 from the praised the "force of his brush" (po tui bi li 頗推筆力) in the standard cursive script (zhangcao 章草), and Dou Ji 竇臮 (mid-8th cent.), author of the rhapsody Shushu fu 述書賦, compared his the forward-running style of his grass-script calligraphies with the blade of a sword (gong zheng ze jian'e daofeng 工正則劍鍔刀鋒). Two of Yu's calligraphies have survived as copies, namely Buzheng tie 步征貼 (grass script), and Shengshi tie 盛事貼 (cursive script, xingshu 行書).