Twelver (,
Athna‘ashariyyah or
Ithna‘ashariyyah; , )
Shia Islam or
Imamiyyah is the largest branch of
Shia Islam. The term
Twelver refers to its adherents' belief in twelve divinely ordained leaders, known as
the Twelve Imams, and their belief that the last Imam,
Muhammad al-Mahdi, lives in
occultation and will reappear as the promised
Mahdi.