Cognomen Soiu (Soiu 
) , all over the world, is a rare surname. The cognomen Soiu is characteristic of Romania, where it is a rare surname, Belgium, where it is a very rare surname, and Canada, where it is an extremely rare surname. Measured by absolute frequency, it is commonest in Romania, the United States, and China. Very seldom, Soiu is the forename as well as the last name.