Some popular theories suggest that Mr. Krabs was killed by SpongeBob, Squidward, or Patrick because they were angry over his high profits. Others believe that he died from a heart attack caused by stress over the Krusty Krab’s impending sale to Plankton. Another theory suggests that he was killed by a vengeful money-lender named Ernest who took out a loan from Mr. Krabs and never repaid it. Finally, some believe that he simply died of old age.