Family name Cy (Cy 
, サイ 
, Сай 
) , globally, is a common last name. The surname Cy is characteristic of Cyprus, where it is quite a common surname, Hong Kong, where it is quite a rare surname, and Macao. Not in comparison with a country's population, it most frequently occurs in China, Ukraine, and Japan. Also, Cy is the forename as well as the last name.