Kalacakra in a Yi-dam(god protector) who turns the wheel of life. Kalacakra is the title of a work in one of the divisions of the Kangyur.
It is possible that Kalacakra is a personification of that work. Kalacakra is usually as a Yidam with four head on each of which is the third eye.
He may have twelve or twenty-four arms but never has more than two legs. In his Yi-dam form, he is dark blue. .