Family name サイダー (Sydor 
, サイダー 
) , across the world, is quite a rare last name. The family name サイダー is characteristic of Poland, where it is quite a rare surname, Canada, where it is a rare surname, and New Zealand. Measured by absolute frequency, it is commonest in Poland, the United States, and Canada. Also, サイダー is the forename as well as the last name.