Family name سياك (Sjaak 
, Ciak 
, Siak 
) , around the world, is quite a rare cognomen. The cognomen سياك is characteristic of Malaysia, where it is quite a rare surname, Singapore, and Poland, where it is a rare surname. In absolute terms, the name is most common in Malaysia, Indonesia, and the United States. Likewise, سياك is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Sjaak | Malaysia, Belgium, United States, Czechia, Netherlands |
| Ciak | Malaysia, Poland, Italy, United States, Indonesia |
| Siak | Malaysia, Poland, United States, Singapore, Indonesia |
| سياك | Iran |