When Ken Allen died in 2000, the San Diego Union-Tribune ran an obituary: "Beloved ape, 29, was renowned escape artist." Yes, Ken Allen wasn't just any primate. The Bornean orangutan, born at the San Diego Zoo in 1971, became famous after a series of escapes in the 1980s. According to the zoo's website, "He never seemed to mind being led back into his enclosure — he just seemed to enjoy the challenge of finding a new way out!" The "hairy Houdini" had a fan club, was the subject of T-shirts and bumper stickers, and even inspired "The Ballad of Ken Allen." In an attempt to figure out how he escaped, the zoo had workers go undercover as tourists and had rock climbers check out the walls. "Ken Allen appeals to everyone's sense of breaking out," psychiatrist and ballad writer Dennis Gersten told the AP. "The irony of it is that he doesn't really want to leave. He breaks out, but he doesn't go anywhere."