Dawn Brancheau was a Sea World trainer who worked with various whales at Sea World Orlando. In 2010, she was tragically killed by Tillikum, the largest Killer Whale held in captivity. Tillikum had killed 2 other people in the past. The incident was documented in the 2013 film Blackfish.
The incident stirred up some controversy concerning the safety of trainers and killer whales. There have never been any reported cases of a wild orca attacking humans. However, when held in captivity, the animals are known to grow bored and frustrated, and have frequently lashed out at trainers. Sea World alone has been the subject of over 70 incidents over the past 30 years. While Brancheau was the first death that has ever resulted in these whale attacks, other incidents have involved thrashing trainers about; dragging trainers to the bottom of incredibly deep pools just to pull them back up and repeat; and attempted devourment.
Brancheau's incident was especially notable not just because she died, but because several parts of her body were held by Tillikum as he stubbornly refused to let them go. Brancheau, a well known perfectionist, taped almost all of her shows so that way she could watch them and improve her performance. The incident was, in fact, caught on tape. Part of it can be seen in Blackfish, but for whatever reason, they were unable to show anything after Tillikum grabbing her arm and getting ready to drag her. This may have been out of respect for her and her family or because Sea World forbade the footage to be shown publicly.
Sea World fought long and hard to make the incident look like an accident instead of an attack. They even went as far as to say that it was because of her ponytail that she was dragged under (despite ponytails having been worn by many other trainers without incident and the fact that she was dragged by her arm, not her hair). Eyewitness reports, as well as the available footage proved that Tillikum attacked Brancheau because she had run out of food to reward him for his tricks, and also because he failed to perform one of the tricks to the fullest. Because of this incident, it is now required by United States law that Sea World's trainers only interact with orca behind a barrier. Many organizations have fought hard to try to make it illegal to keep killer whales in captivity in general.
The remaining footage has never surfaced and it is not known who holds the data. Even though Sea World events are commonly filmed by tourists, somehow not even amateur footage has been seen. There was one video claiming to be of the incident on YouTube, but it was proven fake because the whale in question did not have Tillikum's collapsed dorsal fin and the trainer's suit was an entirely different color. Until it surfaces, this remains another lost video of a tragic event.