Shift is a clever, ancient ape who lives near the Cauldron Pool in the Lantern Waste. He's a neighbor to Puzzle the Donkey, but treats him more like a servant rather than a friend. Shift is completely selfish and a sneak and a liar, and redefines things to fit his own interests. He keeps in contact with Narnia's arch enemies, the Calormenes, and when he finds a lion skin he immediately thinks of a way to put this to use for his own profit.
He tries to pass off Puzzle wearing the lion skin as Aslan, and invites the Calormens to aid him in his deceit. He also tries to make others think that he's a wise old Man, instead of an Ape.
Never in as much control as he thinks he is, Shift does not realize that the Calormens are merely using him to further their own means. Shift drinks too much and becomes incapacitated, and when Tash later enters the Stable, Shift is thrown in by Tirian and is devoured by the Calormen god.