McAnally is a tall, gangly man with a shaved head and of indeterminate age, any age between thirtyfive and fifty. He is a man of few words and few overt expressions, but when he says or emotes something, it is generally noteworthy.
According to Jim Butcher, more will be revealed about McAnally later on the series. He's not a Greek god, nor a scion of the gods. He is, however, dangerous.
In a talk at the Trails West Library, Independence, MO, Jim stated about Mac, "I've already told you who he is, but you'd have to be pretty nerdy..." He went on to say that if someone DID figure it out and asked him about the correct name, he'd say no.(reference needed)