Last name เพ็ญธรรม (เพ็ญธรรม 
, Pentham 
, Pientham ) , in all the world, is a very rare surname. The last name เพ็ญธรรม is characteristic of Thailand, where it is a very rare surname, and India, where it is an extremely rare surname. Much less frequently, เพ็ญธรรม is the forename as well as the last name.