Vi Kyuin "Wellington" Koo (traditional Chinese: 顧維鈞; simplified Chinese: 顾维钧; Pinyin: Gù Wéijūn; Wade-Giles: Ku Wei-chün) (January 29, 1887 – November 14, 1985), Western name V.K. Wellington Koo, was a prominent diplomat under the Republic of China, representative to the Paris Peace Conference of 1919, Ambassador to France, Great Britain, and the United States; participant in founding the League of Nations and the United Nations; and judge on the International Court of Justice at the Hague from 1957 to 1967. .
Koo returned to China in 1912 to serve the new Republic of China as English Secretary to President Yuan Shikai. In 1915 Koo was made China's Minister to the United States and Cuba. In 1919 he was a member of the Chinese delegation to the Paris Peace Conference, led by Foreign Minister Lou Tseng-Tsiang. Before the Western powers and Japan, he demanded that Japan return Shandong to China. He also called for an end to imperialist institutions such as extraterritoriality, tariff controls, legation guards, and lease holds. The Western powers refused his claims and, consequently, the Chinese delegation at the Paris Peace Conference was the only nation that did not sign the Treaty of Versailles at the signing ceremony.
Koo also was involved in the formation of the League of Nations as China's first representative to the newly formed League. He was briefly acting premier and Foreign Minister in 1926-1927 during a period of chaos in Beijing under Chang Tso-lin. He represented China at the League of Nations to protest the Japanese invasion of Manchuria. He served as the Chinese Ambassador to France from 1936-1940, until France was occupied by Germany. Afterwards he was the Chinese Ambassador to the Court of St. James's until 1946. In 1945 Koo was one of the founding members of the United Nations. Afterwards he was the Chinese Ambassador to the United States trying to maintain the alliance between the Republic of China and the United States as the Kuomintang began losing to the Chinese Communists and had to retreat to Taiwan.
Koo retired from the Chinese diplomatic service in 1956. In 1956 he became a judge of the International Court of Justice at The Hague and served as Vice-President of the Court during the final three years of his term. In 1967 he retired and moved to New York City where he lived until his death in 1985.