Quite the opposite of Nurse Ratched's reserved villain, the Wicked Witch from The Wizard of Oz is about as cartoonish of an antagonist as there could be. Of course, in a story like this, the over-the-top evilness of the character works very well.
She is a being of pure evil, threatening Dorothy and even her adorable little dog. The Wicked Witch's terrifying army of flying monkeys surely helps to solidify her place as an iconic villain and likely one that haunted the dreams of many young viewers.