Ouyang, (also O'Young, Owyang, Au Yong, Auyong, Au Yeung) (Simplified Chinese: 欧阳, Traditional Chinese: 歐陽) is one of the most common two-character Chinese surnames in the world, although for a surname, it falls out of the top two hundred as documented by the Language Publication Society, Beijing, in 1990. It constitutes one of the twenty-over two-character surnames that survived till modern times.

The Song Dynasty historian Ouyang Xiu traced the Ouyang surname to Di, a prince of Yue. After his state was extinguished by the state of Chu, Di was given a feoff in what is now southern Jiangsu. He was called Marquis of Ouyangting (欧阳亭侯) and his descendants came to be surnamed Ouyang. Traditionally, Di's ancestry can be traced through his father Wujiang (无疆), the King of Yue, to the semi-legendary Yu the Great.

In terms of distribution Ouyangs have mostly been confined to southern China, especially the areas of southern Jiangxi, central Hubei and eastern Henan, with smaller pockets in Guangdong, Sichuan, Hunan and Guangxi. The most prominent of the Ouyang clans historically was undoubtedly that of Yongfeng (永丰) in Jiangxi, which produced a number of scholars who reached prominence in the imperial bureaucracy. Genealogical lineages and family trees have been established for a number of Ouyang clans around China, showing migration patterns from the Song to the Qing Dynasty.

As with many other two-character Chinese surnames, the words 欧阳 as a pair do not have inherent phrasal meaning. However, by combination of the modern meanings of the individual characters, the name would refer to the "European Sun".

Famous people with this surname

• Ouyang Xiu
• Jin Au-Yeung