"Yu" may represent many different Chinese characters, including 余, 于, 由, 魚 (鱼), 漁(渔), 楀, 俞(兪), 喻 (this character is 35th name on the Hundred Family Surnames poem), 於, 遇, 虞, 郁, 尉, 禹, 游, 尤, 庾, 娛(娱), and 茹 (Rú).
[1] Around 0.41% of the population have the surname 余 in 2002 (over five million), and it is most common in Jiangxi, Zhejiang and Fujian provinces.
During the Zhou dynasty period, the Zheng (state) ruler Duke Wen of Zheng (鄭文公)'s son created a family name Yu (俞).
[3] In Korean, the name is transcribed as Woo (禹 and 于), or Yoo (兪 and 余).
The ancestors of the surname were closely linked with the ancient sage-king named Yu Shun.