Family name Siui (Сюй 
, Siui 
, Сюи 
) , globally, is a rare cognomen. The last name Siui is characteristic of Azerbaijan, where it is quite a rare surname, Armenia, where it is a rare surname, and Kyrgyzstan. Measured by absolute frequency, it is the most numerous in Russia, Ukraine, and Azerbaijan. Much less frequently, Siui is the forename as well as the last name.