One of the city’s fattest felines has died — of a broken heart.

SpongeBob, the 33-pound tabby who fascinated New Yorkers earlier this summer, has gone to the great kitty-litter box in the sky after suffering from an inoperable heart growth.

SpongeBob — who was adopted just two months ago from an animal shelter — could not undergo surgery because the high dose of anaesthesia that would have been required to knock out a cat of his size would also have proved fatal.