Stiyl Magnus is an antagonist but sided with Touma and his friends in the novel, anime series A Certain Magical Index.
His blond hair is dyed red and hangs on his shoulders. He wears a black priest robe and has a silver ring on each of his ten fingers, earrings on both ears, and a barcode tattoo under his right eye. Despite being fourteen, Stiyl is a tall man with a strong perfume smell, and is often seen having a cigarette in his mouth, as he is an extremely heavy smoker. He claims a world without nicotine would be hell and that he dislikes Academy City since it's hard to get cigarettes as a minor.
Because of this and along with his personality, Stiyl seems more mature than Touma despite being younger than him.
He is physically very weak, as shown when he was beaten by Touma with a single punch (though this is explained as Innocentius needing vast amounts of energy, rendering Stiyl's body weaker than most others'.)