The Grinch

"The Whos down in Whoville loved Christmas a lot... but the Grinch, who lived just north of Whoville, did not."

- Dr. Seuss

The Grinch is the titular protagonist and antihero of Dr. Seuss' How the Grinch Stole Christmas!. He is a green grinch who used to hate the Whos and the season of Christmas even more. So, the Grinch planned to "steal" Christmas by sneaking out in the disguise of Santa Claus and stealing all of the Who's stuff. In the end, after seeing the Whos sing (even without their presents), the Grinch's heart softens and he becomes a much nicer person.

The Grinch later appeared in Halloween Is Grinch Night (where he tried to terrorize the Whos into bringing his Paraphernalia Wagon on his way) and The Grinch Grinches the Cat in the Hat as the main villain. (where he tried to do so).

He was voiced by Boris Karloff in the Christmas special, Hans Conried in Halloween is Grinch Night and portrayed by Jim Carrey in the live-action movie.

Personality
"It could be because his head wasn't screwed on just right, or his shoes were too tight, or perhaps, the best reason of all was that because his heart was two sizes too small."

- Dr. Seuss

In the live-action film, the reason for his hatred of Christmas was because of him being bullied by other kids for his appearence.

Around Christmastime at school, when the kids (especially Augustus, who insulted him first) laughed at him for his poor attempt at shaving his beard (having cuts all over), the Grinch finally snapped and destroyed everything in the classroom (including the very gift he made for Martha May just when he felt excited about Christmas for once) and threw the Christmas tree at the kids, sending them into panic. Declaring that he now hated Christmas, the Grinch then left the school and went to live in on Mt. Crumpit.

Trivia

 * The Grinch is constantly believed to be the main antagonist of the book, 1966 cartoon, and film. However, this isn't true as the Grinch is simply an antihero who was misunderstood.
 * Unlike the book or 1966 cartoon where the Grinch is a smart, scheming individual,  the film shows him to be a comical insane person with the scheming qualities.