Cognomen Goonathilaka (Goonathilaka 
) , all over the world, is a rare family name. The surname Goonathilaka is habitual in Sri Lanka, where it is quite a rare surname, Malaysia, where it is a rare surname, and New Zealand, where it is a very rare surname. In absolute terms, this name is the most popular in Sri Lanka, Malaysia, and the United States.
| VARIANT | COUNTRY |
|---|---|
| Goonathilaka | New Zealand, Sri Lanka, United States, Malaysia |