Kalki in the Vishnu Purana

When the practices taught by the Vedas and the institutes of law shall nearly have ceased, and the close of the Kali age shall be nigh, a portion of that divine being who exists of his own spiritual nature in the character of Brahma, and who is the beginning and the end, and who comprehends all things, shall descend upon earth: he will be born in the family of Vishńuyaśas, an eminent Brahman of Sambhala village, as Kalki, endowed with the eight superhuman faculties. By his irresistible might he will destroy all the Mlechchhas and thieves, and all whose minds are devoted to iniquity. He will then reestablish righteousness upon earth; and the minds of those who live at the end of the Kali age shall be awakened, and shall be as pellucid as crystal. The men who are thus changed by virtue of that peculiar time shall be as the seeds of human beings, and shall give birth to a race who shall follow the laws of the Krita age, or age of purity. As it is said; "When the sun and moon, and the lunar asterism Tishya, and the planet Jupiter, are in one mansion, the Krita age shall return."