No one has cheated death in comics more than the Joker. Even his debut comic concluded with him seemingly perishing after being stabbing in the heart. He has "fallen to his death" from a lighthouse, motorway, cliff, trap-door, cave, boat, blimp, and train - but always manages to land juuuuuust right to live another day.
If you thought shooing the demented clown would be a sure way to kill him, guess again. He was shot eight times in The Demon Laughs storyline, but was revived with a Lazarus Pit. He got shot in the forehead at point-blank range, but was back to his normal self soon after (well, normal by his standards).
Nightwing beat the Joker to death after he thought the Clown Prince of Crime killed Robin, but he was resuscitated with CPR. Batman killed Joker killed in the finale of Endgame, but his body was regenerated with a chemical called Dionesium.
He has died in many non-canonical tales including Injustice: Gods Among Us, The Dark Knight Returns, Batman Beyond: Return of the Joker, and Batman: Arkham City. But as he has proven in those stories, even if the Joker dies, he still finds a way to torment Batman.