The Snatcher (his real name, Vladus Lokowitchki) is an antagonist in The Amazing World of Gumball episode "The Mirror".

The Snatcher started out as a mortal man named Vladus Lokowitchki, where he fell in love with a beautiful female ghost dwelling in mirrors. Vladus used a forbidden book to give him the ability to touch the beautiful ghost and fall in love with her, and they had a child together. However, after using the forbidden book, Vladus was cursed to forever live a lonely existence inside mirrors. Several years of loneliness degenerated him into a vengeful, spiteful ghost, who will then snatch any person into a mirror in hopes to be released from the curse.

Years later, The Snatcher cursed Gumball for refusing to forward a chain email, despite Darwin's advice. First, he took Gumball's money, then his friends, and then his family. After that, he reveals himself to Gumball and Darwin at night, in an attempt to snatch Gumball's soul.
Screen shot 2014-11-02 at 1 24 44 PM

The Snatcher attacking Gumball

Luckily, Carrie arrives at Gumball's house with the Forbidden Book after hearing the story of Gumball being cursed. Carrie led Gumball and Darwin to the attic, and defeat The Snatcher by shining light at him and Carrie tossed the Forbidden Book at him. After that, Vladus and Gumball's family were free from the curse, and Vladus was reunited with his daughter, Carrie.