Last name Эрдей (Erdei 
, Erdey 
, Эрдей 
) , across the world, is a common cognomen. The surname Эрдей is habitual in Hungary, where it is quite a common surname, Romania, and Serbia, where it is quite a rare surname. Not in comparison with a country's population, this name is the most popular in Hungary, Romania, and the United States. Very seldom, Эрдей is the forename as well as the last name.