The Joker in The Dark Knight looks different from the other Jokers that came before. Other Jokers have fixed or painted on smiles
but Heath Ledger’s Joker has scars that extend his smile into a freakish sight. The Joker gives a few conflicting explanations for how he got his scars -- first he says he got them from his abusive father. In his second story, he says he gave himself the scars after his wife was disfigured by loan sharks. Later he’s about to tell Batman a third story of how he got his scars, but he never gets the chance. It was a calculated move on director Christopher Nolan’s part to never give a concrete reason for the Joker’s scars.
Nolan has said, “In narrative terms we didn't want to humanise him, we didn't want to show his origins, show what made him do the things he's doing because then he becomes less threatening.” The Joker embodies anarchy and destruction that can’t be controlled or understood, so the conflicting stories of how he was scarred refuse to give us a resolution to that chaos.

The scars have multiple symbolic meanings throughout the story. The grotesque twist on a clown’s red mouth visually reflects a sense of humor taken to a sick, horrifying extreme -- which is the Joker’s trademark. The Joker likes to toy with his victims and treat his killings like a game. Batman is one of the most serious, noirish superheroes out there, so the Joker’s scars mark him as the antidote to all of the doom and gloom. Yet even though the scars approximate a smile, if we look closer, this is a terrifyingly unhappy face. The Joker’s scars also represent a perversion of love. A key similarity in the two scar stories he tells is the relationship element, both anecdotes describe a twisted relationship in which the Joker didn’t get the love he was seeking. In the first story, his father, who should have been a protective presence, only wanted to hurt him. And in the second story, he disfigured himself for his wife, but his strange romantic gesture backfired.