Family name 西斯 (Sies 
, Seath 
, 西斯 
) , throughout the world, is quite a rare cognomen. The cognomen 西斯 is habitual in Malta, where it is quite a rare surname, Austria, and Netherlands. Not in comparison with a country's population, it most frequently occurs in the United States, Germany, and the United Kingdom. Also, 西斯 is the forename as well as the last name.