Mazdak
Mazdak (Middle Persian: 
) (died c. 524 or 528) (also Mazdak the Younger) was a Zoroastrian prophet, Iranian reformer and religious activist who gained influence under the reign of the Sassanid Shahanshah Kavadh I. He claimed to be a prophet of Ahura Mazda, and instituted communal possessions and social welfare programs. He has been seen as a proto-socialist.
Mazdakism
Mazdak was the chief representative of a religious and philosophical teaching called Mazdakism, which he viewed as a reformed and purified version of Zoroastrianism, although his teaching has been argued to display influences from Manichaeism as well. Zoroastrianism was the dominant religion of Sassanid Persia, and Mazdak himself was a Zoroastrian priest, or mobed, but most of the Zoroastrian clergy regarded his teaching as heresy. Information about it is scarce and details are sketchy, but some further details may be inferred from the later doctrine of Khurramism, which has been seen as a continuation of Mazdakism.
