Surname Касумьян (Kasumyan 
, Касумьян , Kasumian 
) , all over the world, is a very rare cognomen. The cognomen Касумьян is characteristic of Russia, where it is a very rare surname, Georgia, and the United States. Measured by absolute frequency, it is commonest in Russia, the United States, and Canada. Much less frequently, Касумьян is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Kasumyan | Canada, United States, Russia |
| Касумьян | Russia |
| Kasumian | Georgia, United States |