Cognomen Rethus (Rethus 
) , across the world, is a very rare family name. The last name Rethus is habitual in Australia, where it is a rare surname, New Zealand, where it is a very rare surname, and India, where it is an extremely rare surname. Very seldom, Rethus is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Rethus | Australia, India, New Zealand, Philippines |