"See, there were these two guys in a lunatic asylum? and one night, one night they decide they don't like living in an asylum any more..." - Joker - The Killing Joke
He's an unnamed engineer who quits his job at a chemical company to become a comedian, only to fail miserably. Desperate to support his wife, he agrees to guide two criminals through the chemical plant he previously worked at so that they can break into the company next door. During the planning, the police inform him that his wife has died in a household accident. Grief-stricken, the engineer tries to withdraw from the plan, but the criminals strong-arm him into keeping his commitment to them.
At the plant, the criminals make him wear a helmet to become the infamous Red Hood. Unknown to the engineer, the criminals plan to use this disguise to divert attention away from themselves and lay the blame on someone more recognisable. Once inside, they run into security personnel, and a gun fight ensues. The criminals are gunned down and the engineer finds himself confronted by Batman, who is investigating the incident.
Terrified, the engineer jumps into the chemical plant's waste to escape Batman and is swept through a pipe leading to the outside. Once outside, he discovers, to his horror, that the chemicals have permanently bleached his skin chalk-white, stained his lips ruby-red and dyed his hair bright green. This disfigurement, compounded with the man's misfortunes of that day, drives him completely insane and marks the birth of the Joker.
All it takes to change your life is 'one bad day'.
In the Batman Miniature Game, The Killing Joke Joker is a Leader for a Joker crew.
At 100 Reputation, the Joker costs a lot to hire but he is worth all of it.
His trusty Acid Flower lets him damage people at Short Range and if them come any closer he can take them down with a Knife and his Baton.
His appearance and character can Intimidate and Demotivate the enemy stopping them from attacks or even acting at all at times.
Kaos Agent and Kill Them let the Joker play lots of tricks leads his crew but giving then additional action counters and letting them move counters around with trickster.
The Killing Joker Joker is more of a front and centre Leader for the crew. He can cause a lot of Kaos for the opponent and laugh manically as he does.