Last name Niilus (Niilus 
) , worldwide, is a very rare surname. The last name Niilus is habitual in Estonia, where it is quite a rare surname, Argentina, where it is a very rare surname, and the United States, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Niilus | United States, Argentina, Estonia |
| jaan niilus (b. 1881) |
|
|
| valter niilus Estonian linguist, EE (b. 1913) |
|
|
| leopoldo j. niilus AR (b. 1930) |
|