Cognomen Руса (Руса 
, Rusa 
, Roosa 
) , in all the world, is a common last name. The last name Руса is characteristic of Bulgaria, where it is a common surname, Latvia, where it is quite a rare surname, and North Macedonia. Measured by absolute frequency, it is the most numerous in Bulgaria, the United States, and Indonesia. Likewise, Руса is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Руса | Kazakhstan, Russia, Ukraine, Bulgaria |
| Rusa | Romania, Bangladesh, United States, India, Indonesia |
| Roosa | Finland, Venezuela, United States, India, Indonesia |
| Rousa | Greece, Brazil, United States, India, Algeria |