Cao (Mandarin pronunciation: [tsʰɑʊ̯]) is the Pinyin romanization of several Chinese family names, including 曹 Cáo, 操 Cāo, 草 Cǎo along with other possible rarer characters. Using the Wade-Giles system, Tsao is romanized as Ts'ao, also spelled Tsao.
Among these names, 曹 Cáo is the most common and listed as the 26th surname in the Hundred Family Surnames. The surname 曹 Cáo originated in the Chinese vassal state of Cao, founded by Ji Zhenduo during the Zhou Dynasty. Cao Cao (曹操) was a warlord and the penultimate Chancellor during the final days of the Eastern Han Dynasty. His son Cao Pi subsequently proclaimed himself emperor of Wei. One branch of Cao Cao's descendants adopted his given name 操 Cāo as family name. The Zhu is also a branch of the Cao (曹) family.
曹 Cáo is also found in Korea, with the romanizations of Cho or Jo.