The Bane is a creature of the dark, and is the only of it's kind. In The Last Apprentice book 2, there is a map of the Bane's domain in the back of the book, on the map is a drawing of the Bane, though it is not clear, the Bane resembles a large lion, though the creature can change shape. He used to be one of the Old Gods but his status was removed when his power depleted, following his binding beneath Priest Town by Naze.
The Bane is a ancient god who was worshiped by the segantii "the little people".
The Bane tore the little people into poverty and demanded a annual sacrifice of the King Heys' sons, one each year till none remained alive. But Naze the Kings 7th and last son managed to bind The Bane. He did this by letting The Bane feed off of him and in return grant him 3 wishes,
"I made a pact giving it my blood to drink. Three more times after could it drink, and in return three times it must obey my commands."
His first wish/command was that The Bane keep well clear of the area that Nazes father and brothers were buried. His second command was for the bane to go on a quest to the ends of the earth in search of knowlage, it went and did not return for a month and a day. In that time Naze told his people to build the silver gate. After giving the bane his blood for the final time he screamed out his last command,
"You are bound to this place! Confined to the inner catacombs with no way out. but because i would wish no being, however foul, to endure without even a glimmer of hope, i have built a silver gate. if anyone is ever foolish enough to open that gate in your presense, you may pass through it to freedom. however, following that if you ever return to this spot, you will be bound here for all eternity."
in making his final wish/command the bane in a rage killed the prince Naze where he stood with the press, and after getting bored with the bones in "his" catacombs the bane poked them one by one back through the gate so that the little people could finaly burry Naze with his family.
In the second book, ( Curse Of The Bane) Tom has a nightmare where he finds a note in his home ( which was destroyed and desserted in the nightmare) saying
"Your Dad's, Jack's, Ellie's and Mary's graves are up on Hangman's Hill. You'll find your mother in the barn"
So Tom goes up to the barn and sees Mam, angry. She screamed " Don't Look at Me Tom! Don't look at me! Turn away now!"
Tom did turn away but saw Mam's mutation out of the corner of his eye. Then the Bane spoke inside his head saying
The moon shows the truth of things, boy. You know that already. All you have seen is true or will come to pass. All it takes is time.
Then, in the sixth book while fighting The Ordeen, Tom runs up to see Mam, becoming less and less human. She screams the same words " Don't look at me Tom! Don't look at me! Turn away Now!" Becoming the same mutated creature that Tom saw in his nightmare.