Family name Когой (Kogoj 
, Kogoy 
, Когой 
) , globally, is quite a rare surname. The last name Когой is habitual in Slovenia, where it is quite a common surname, Austria, where it is quite a rare surname, and Serbia. Not in comparison with a country's population, it is the most numerous in Slovenia, Austria, and Italy. Very seldom, Когой is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Kogoj | Slovenia, Serbia, United States, Austria, Italy |
| Kogoy | Australia, Philippines, United States |
| Когой | Russia, Kyrgyzstan |
| Kogoi | Australia, France, Argentina, United States, Italy |