Surname Tadeus (Tadeus 
, Тадеус 
) , all over the world, is a rare family name. The family name Tadeus is habitual in Namibia, where it is quite a rare surname, Tanzania, where it is a rare surname, and Indonesia, where it is a very rare surname. More prevalently, Tadeus is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Tadeus | Germany, Tanzania, Brazil, Indonesia, Namibia |
| Тадеус | Russia, Ukraine |