Family name Круглиак (Krugliak 
, Kruglyak 
, Круглиак ) , in all the world, is a rare surname. The surname Круглиак is characteristic of Israel, where it is quite a rare surname, Estonia, where it is a rare surname, and Romania. Measured by absolute frequency, it is the most numerous in the United States, Israel, and Russia. Very seldom, Круглиак is the forename as well as the last name.