In Mandaeism, Sin or Sen () is the name for a divine figure associated with the Moon (Mandaic sira, .
Sen is one of the embodiments of the classical planets (), who are part of the entourage of Ruha in the World of Darkness.
In Mandaean astrology, Sin is associated with miscarriages and abnormal births. Other names for Sin include Agzÿil, Ṭaá¹Âmÿil, á¹¢aurÿil, and Sira. Sin's name is derived from the Akkadian language name Sënu, a moon deity in ancient Mesopotamian religion.
Chapter 53 of the Mandaean Book of John (also in Right Ginza 15.4) is about Sin.