Joker Venom was a deadly toxin utlized by the Joker and his crew to wreak havoc on Gotham City. For years the toxin's ingredients down to the base element were unknown, however, it was later discovered by the Batman to contain Dubnium, originally called Hahnium and abbreviated to Ha. The Venom, depending on the dose, was either lethal or non-lethal. The non-lethal one simply sent one's motor functions into a temporary state of decay and fixiated their muscles with a smile. The lethal one fixed one's facial muscles into a smile and easily deteriorated their body.