Cognomen เพ็ญกาญจน์ (Penkarn 
, เพ็ญกาญจน์ , Phenkarn ) , in the entire world, is a very rare last name. The surname เพ็ญกาญจน์ is habitual in South-eastern Asia, particularly Thailand, where it is a very rare surname. More prevalently, เพ็ญกาญจน์ is the forename as well as the last name.