Family name Rathnasiri (Rathnasiri 
) , across the world, is quite a common surname. The cognomen Rathnasiri is habitual in Sri Lanka, where it is quite a common surname, Qatar, where it is quite a rare surname, and United Arab Emirates, where it is a rare surname. Not in comparison with a country's population, it is the most numerous in Sri Lanka, Saudi Arabia, and United Arab Emirates. Very seldom, Rathnasiri is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Rathnasiri | Kuwait, United Arab Emirates, Saudi Arabia, Sri Lanka, Qatar |