According to Nancy Black, a marine biologist, killer whales don't normally kill people, and there has never been a documented case of a whale killing a person in the wild. There have been some documented cases where trainers have been killed by killer whales, or orcas, at water parks.
Killer whales swim in deep waters and avoid swimming along shorelines where people often swim. Orcas attack whales and other sea animals, which resulted in its reputation for aggressiveness among humans. Sailors who witnessed orcas attacking marine animals came to label orcas as "whale killers," but "killer whales" subsequently became a more popular name.
An orca has a playful nature, but its power and wild nature can get trainers injured or killed. In 2010, a trainer was unintentionally drowned by a killer whale, but marine biologists theorized that the animal was bored in captivity and simply wanted a companion to play with underwater.