1976 - December 12, 2003: Age 27
Keiko was the orca who starred in the first Free Willy movie in 1993. He was captured near Iceland (age 3) and sold to an aquarium there. From there, he was sold to Marineland in Ontario, and then in 1985 to an aquarium in Mexico.
The irony of his appearance in a film about a captive whale released into the wild was not lost on the public, and a movement (vigorously supported by the film studio) to free Keiko, the "real" Willy, was begun.
The plan was controversial. On the one hand, it had enormous public appeal. On the other, Willy had been in captivity since the age of three, so probably had limited survival skills and no links to other whales in the wild. However the plan went ahead, and he was airlifted to Oregon in January 1996 where a special facility had been built for rehabilitating his health, which was not good. Things went well, and by September 1998 he had gained more than a ton in weight and was flown to Iceland for training.
His training included supervised "walks" in the open ocean, during which he frequently interacted with wild whales. During one of these, his trainers lost track of him, but he turned up two months later in September 2002 following a boat in Norway. When first spotted he was in good health, having travelled over 1,000 miles in the North Atlantic. However in Norway he allowed fans to play with him and crawl on his back. Local biologists and his trainers felt the interaction with humans was a step in the wrong direction, and persuaded him to move to a more remote location, where they hoped that he might be picked up by a passing whale pod and led back into the open ocean. This did not happen, and his trainers had to continue to feed and care for him.
Keiko died of pneumonia in December 2003. After showing signs of lethargy and lack of appetite for a day, he suddenly beached himself and died in the early evening of December 12. At 27 he was young by the standards of wild orca, but old by the standards of captive ones: he was the second oldest male among captive orca.
Sources: Wikipedia, Keiko.com