South Africa is mourning the death of Max, a 200kg gorilla who shot to fame after braving bullet wounds to overpower an armed robber in his zoo.
Male gorillas tend to guard their territory fiercely against intruders
The crime-fighting primate died in his sleep, according to Johannesburg zoo.
The gorilla became a national hero in 1997, when he confronted a thief who jumped into his enclosure while being pursued by the police.
Max bit the hapless intruder on the buttocks and kept him pinned to a wall, despite being hit by two bullets.
The burglar was apprehended, but not before two policemen who had chased him into the enclosure also received bite wounds to the buttocks and arm.
Surgeons later removed gunshots from Max's jaw and shoulder; he went on to make a full recovery.
Max's cult status was assured in crime-torn South Africa, which seized on him as a heroic mascot in the fight against felony.
Cuddly toys were crafted in his image and Johannesburg police honoured the gorilla with a bullet-proof vest - though this turned out to be many sizes too small.
"Max helped raise community awareness about crime... it's sad," said a police spokesman, responding to news of his demise.
A zoo spokeswoman said a post-mortem would be carried out to establish what killed the 33-year-old ape.
The robber, Isaac Mofokeng, was sentenced to 40 years in prison for a string of offences.
At his trial in 1999, Mofokeng described how he thought his "last hour had come".
"The first thing the gorilla did was rip my jeans and bite me on the buttocks," he said.
"Max then dropped me... (He) ran around and became violent, grabbed me by my right leg, swung me around and threw me against the wall and I became dizzy," Mofokeng told the court.