Elvis

https://www.mirror.co.uk/3am/celebrity-news/elvis-presley-sustained-secret-horror-23318182

He once said: "Presley's chronic constipation - the result of years of prescription drug abuse and high-fat, high-cholesterol gorging - brought on what's known as Valsalva's maneuver. Put simply, the strain of attempting to defecate compressed the singer's abdominal aorta, shutting down his heart."

Others claimed he'd died from a drug overdose, but when the investigation was reopened in 1994, coroner Joseph Davis disagreed.