Family name ประจัน (Prachan 
, ประจัน ) , in the entire world, is a rare cognomen. The family name ประจัน is characteristic of Thailand, where it is a rare surname, Malaysia, where it is an extremely rare surname, and the United States. Measured by absolute frequency, it is commonest in Thailand, the United States, and India. More prevalently, ประจัน is the forename as well as the last name.