Cognomen טרויאן (Troian 
, טרויאן 
) , in the entire world, is quite a rare family name. The cognomen טרויאן is habitual in Moldova, where it is quite a rare surname, Estonia, where it is a rare surname, and Brazil. Measured by absolute frequency, it most frequently occurs in Brazil, Italy, and Moldova. Much less frequently, טרויאן is the forename as well as the last name.