An evil being with no eyes hidden within a veil. All he wants to do is wreak havoc. He first took Sarah Jane out of her Time Line and replaced her with Andrea Yates- something that never happened. Because of this, the end of the world nearly happened. Secondly, he tempted Sarah Jane to save her parents that she never knew before they died and she did so and the whole Earth paid the price. Without parents, she never met the Doctor and without Sarah Jane, the Doctor failed to save the Earth and it was enslaved by the Trickster. During an episode of Doctor Who, Turn Left, one of the Trickster's Brigade, a Time Beetle, latched onto Donna Noble and made her turn right instead of left. She never met the Doctor, the Doctor died and so did everyone else in the whole universe. Finally, the Trickster tricked Sarah Jane's fiancé into saving his own life and marrying Sarah Jane. Although he did love Sarah Jane, if Sarah Jane married him, she'd forget about the Earth and leave it wide open to attacks. With the help of the Doctor and the sacrifice of her fiancé, the Earth was once again safe.