In Tim Burton's 1989 Batman movie, the Joker is directly responsible for Batman's existence as it was he - in his Jack Napier persona, prior to actually becoming the Joker - who killed Bruce Wayne's parents in that dank alley all those years ago. After a night at the theatre, Bruce and his parents were confronted by two mobsters - one of them being Jack Napier - who robbed his mother of her jewellery before shooting his mother and father. Batman came to realise this when the Joker confronted him in his apartment in the (then) present day and asked him "Have you ever danced with the devil by the pale moonlight?" - the exact the same question Jack Napier asked him after shooting Thomas and Martha Wayne. The death of one's parents - particularly at such a young age - is terrible. Having them taken away from you so needlessly is even worse and, therefore, surely this is the worst thing the Joker has ever done to Batman? Well, you'd think so, but this final entry takes some beating...
