Surname สิทธิวัจน์ (สิทธิวัจน์ 
) , in all the world, is a very rare last name. The surname สิทธิวัจน์ is habitual in South-eastern Asia, particularly Thailand, where it is a very rare surname. Likewise, สิทธิวัจน์ is the forename as well as the last name.