Cognomen Kaidu (海都 
, Kaidu 
, Хайду 
) , worldwide, is a rare surname. The last name Kaidu is characteristic of Tanzania, where it is a very rare surname, Malaysia, and China, where it is an extremely rare surname. Not in comparison with a country's population, the name is most common in China, Tanzania, and India. More frequently, Kaidu is the forename as well as the last name.