Cognomen Sisii (Sisii 
) , all around the world, is a rare last name. The last name Sisii is characteristic of Papua New Guinea, where it is quite a rare surname, Algeria, where it is a rare surname, and Australia, where it is a very rare surname. In absolute terms, the name is most common in Papua New Guinea, Algeria, and France. Likewise, Sisii is the forename as well as the last name.