Heath Ledger’s reincarnation of the Joker is one of the best examples of a comic-book villain in modern cinema. But what makes so striking a performance for cinema fans?

One answer lies in his catch phrase: “Why…so…serious?”.

In The Dark Knight,  we’re shown a more erratic Joker than before. He’s shed the clownish dancing and the gag props from earlier Batman films, opting for more nightmarish weapons and a harrowing backstory. He doesn’t have a cartoon personality anymore, and this is apparent in his dialogue – there are no cheesy puns or catch phrases here. Instead, as he murders his victims, he asks them the supposedly innocuous question, “Why so serious?” as if he’s checking to see why they’re not enjoying it as much as he is. It’s a twisted line – like he’s making a joke or a game out of a deathly serious situation. It’s a self-parody of the earlier, goofier versions of himself – but this line is definitely a clear turning point at which he sets himself apart from his predecessors.

The Dark Knight gives us a Joker who is more human than ever. Without all of the caricature-like frills, he’s just a man gone mad – and that’s the most terrifying thing about him. We’re definitely not laughing at this clown anymore.