The only reliable report I know about is a 1972 attack on a surfer. A transient-type killer whale bit the dude and then left.
To the untrained this may indicate that the whale didn't like the surfer... keep in mind that "bite and leave" is the default feeding tactic for these things. Great whites have similar behaviours. You wait for the prey animal to weaken from shock and blood loss, and then return. The strategy is theorized to minimize the prey injuring the shark and/or killer whale.
For well over a hundred years folks have been told to get out of the water when killer whales are spotted. The same is obviously true for great whites. Problem with great whites is that they're usually alone and much harder to see from the surface... this is thought by many to be the main reason you have a lot more documented attacks in comparison to the near-nil reports from killer whales.
People generally aren't tasty to marine life, also, but this won't stop a critter from biting you if it's never tasted you before. Killer whales are incredibly curious and resourceful, and I have no doubt of their inkling to bite people. Having seen a friend of mine bitten to the bone by a baby dolphin during playtime, the damage from something a couple tons bigger is frightening to imagine.
Ever seen the video of the pilot whale grabbing the snorkeler and dragging her down, while the other whales watched? THAT'S CREEPY.