Tash is the Bigger Bad of The Chronicles of Narnia series. He is the demonic God of Calormen, an empire in the south of Narnia, and the rival of Aslan, the Great Lion that is worshipped by Narnians.
He is considered to be the Patron of Calormen, to which great temples were built and his worshippers offered human sacrifices. Tash, like Aslan, has his own country, likely a hellish place, where the Evil Narnians and those that opposed Aslan went after their deaths.
Tash is mentioned in The Horse and His Boy as an emaciated, humanoid being, much taller than a man, with a demonic vulture-like head, four arms with great clawed hands and surrounded by an aura of coldness and death.
HistoryTash is a god of the Calormenes and is a minor antagonist in Narnia and a supporting antagonist in the Last Battle. In The Last Battle it is seen that he strikes fear and dread into those he meets, particularly in one scene: Tirian, Jill, Eustace and Poggin (when he passes by them on the way to the Stable Hill). In the Last Battle, Shift claims that the Carlomene's god Tash and Aslan the Lion are the same and called them Tashlan; however, this unintentionally summons Tash to the Stable. Rishda the Tarkaan inadvertantly calls Tash into Narnia and the King of Narnia Tirian arrives with his followers and he throws Shift into the Stable, where the dreaded Calormen god devours him. While fighting the Calormens, Tirian fights Rishda and throws him through the Stable, which leads to Aslan's Country, where Tash appears again and takes Rishda in as a sacrifice and as punishment for his sins. The High King Peter appears and banishes Tash from Narnia in Aslan's name, to which Tash vanishes with Rishda.
While Aslan appears to be God, Jesus or the Messiah in his Narnian form, Tash (as the opposite figure) could be considered Satan, the Antichrist or another Satanic figure of Narnia. Aslan's name repels Tash away from his country, similar to how the Devil flees from the name of Jesus Christ. Also, since Evil Narnians went to Tash's Country, it is possible that this country is the Narnian Hell, while Aslan's Country is a more heavenly place.
Tash's birdlike appearance may also represent the pagan deities that were worshipped in ancient Mesopotamia and Egypt, such as Baal, Molech and Nisroch, while Tash's four arms may hint an influence from Hinduism. Interestingly, the word "tash" can be translated to "stone" or "rock" in Turkish; similar to how "aslan" is translated to "lion" in the same language.
The Voyage of the Dawn Treader
The Silver Chair
The Horse and his Boy