Superman: The Man of Steel #75
With all the seriousness that befits the occasion, we regret to inform you that Superman's greatest foe, Mxyzptlk, has died. That's right, he's dead, dead, dead. Join us as some of Metropolis mourns, raising their voices in unison for a chorus of "Mxy, we hardly knew ye; in fact, we could hardly pronounce ye name." There won't be a dry eye in the house…Mxy has a squirting flower in his casket.