Wu Youxun (simplified Chinese : 吴有训 ; traditional Chinese : 吳有訓 ; pinyin : Wú Yǒuxùn ; Wade–Giles : Wu Yu-hsun ; 26 April 1897 – 30 November 1977), also known as Y. H. Woo, was a Chinese physicist. His courtesy name was Zhèngzhī (正之).