Family name سيس (Sis 
, Cees 
, سيس 
) , throughout the world, is a common last name. The cognomen سيس is characteristic of Guatemala, where it is quite a common surname, Myanmar, and Norway, where it is quite a rare surname. Not in comparison with a country's population, the name is most common in Guatemala, Myanmar, and Indonesia. Also, سيس is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Sis | Indonesia, Guatemala, India, Myanmar, Netherlands |
| Cees | Indonesia, Malaysia, United States, India, Netherlands |
| سيس | Sudan, Morocco, Egypt, Algeria, Iraq |
| Syse | Norway, United Kingdom, Spain, United States, Poland |