Why The Joker Killed Himself (The Batman Who Laughs #1) chan 8 years ago Advertisements The Joker killed himself so the toxin in his heart would infect Batman, turning him into another Batman Who Laughs. From – The Batman Who Laughs #1 Share this: Share on X (Opens in new window) X Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on Tumblr (Opens in new window) Tumblr Share on Pinterest (Opens in new window) Pinterest