One of the main characters in Wuthering Heights by Emily Bronte. He was adopted into the Hindley family; the daughter, Catherine, loved him, and he loved her. He was, however, very dark and brooding and tormented. Many women have a crush on this fictional character because for some inexplicable reason, women seem to like dark, brooding tormented men in works of fiction, though they often don't in real life. Heathcliff served him both as a first and last name. He is famous for walking alone out on the English moors.
"He's such a Heathcliff." (Said about someone with a short temper prone to spend time by himself brooding about his horrible life.)