Surname Койн (Keun 
, Coyne 
, Койн) , around the world, is a common family name. The last name Койн is characteristic of Ireland, where it is quite a common surname, Australia, where it is quite a rare surname, and the United Kingdom. Measured by absolute frequency, it most frequently occurs in the United States, the United Kingdom, and Ireland. Very seldom, Койн is the forename as well as the last name.