The "Sabians" aka Johnite Christians
An Iranian Gnostic Christian sect which drew heavily from Jewish legend and scripture but saw a dualistic battle between Light and Darkness being played out for Men's Souls. Probably more directly related to Zoroaster influences, but their literature focuses on Hebrew texts, while their anti-Monotheism indicates other influences. Great reverence for John the Baptist, but not Jesus the Christ;
Seemingly independent at first from Mani or the Essenes, they predate the schools of Valentinus and Iamblichus, and we only learned about them in the early 1900s because Ms. Ethel Stefana Drower aka Lady Drower studied them, and in the news most recently as their Yazidi descendents have been threatened in Iraq by Muslim extremists.
Resources: http://en.wikipedia.org/wiki/Mandaeism ;