The demon Marax appears in the grimoires The Discoverie of Witchcraft, The Grand Grimoire, Pseudomonarchia Daemonum, and The Lesser Key of Solomon
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Twenty-first Spirit is Marax. He is a Great Earl and President. He appeareth like a great Bull with a Man's face. His office is to make Men very knowing in Astronomy, and all other Liberal Sciences; also he can give good Familiars, and wise, knowing the virtues of Herbs and Stones which be precious. He governeth 30 Legions of Spirits, and his Seal is this, which must be made and worn as aforesaid, etc.