Cognomen Ilgan (Ильган 
, Ilgan 
) , throughout the world, is a very rare surname. The surname Ilgan is habitual in Turkey, where it is a rare surname, Georgia, where it is a very rare surname, and Germany, where it is an extremely rare surname. Measured by absolute frequency, it most frequently occurs in Turkey, Germany, and Philippines. Very seldom, Ilgan is the forename as well as the last name.