Cognomen Gonasillan (Gonasillan 
) , across the world, is a very rare last name. The last name Gonasillan is characteristic of Sub-Saharan Africa, particularly South Africa, where it is a very rare surname. Much less frequently, Gonasillan is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Gonasillan | South Africa |