Cognomen همايون (همايون 
, Homayoun 
, Homayoon 
) , around the world, is quite a common last name. The cognomen همايون is habitual in Iran, where it is quite a rare surname, Cyprus, and Denmark, where it is a rare surname. Measured by absolute frequency, it is commonest in Iran, Afghanistan, and the United States. More prevalently, همايون is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| همايون | Saudi Arabia, Iraq, Afghanistan, Iran |
| Homayoun | Afghanistan, United States, Bangladesh, Canada, Iran |
| Homayoon | Afghanistan, United States, Canada, Indonesia, Iran |