Orca is a killer whale who kills and eats people in the movie Orca.
Orca is an abnormally aggressive killer whale, and in constrast to the real life animal, was fond of hunting humans - however things went from bad to worse when, in an effort to end of the orca's rampage the hapless humans accidentally killed his mate instead.
Orca showed himself to be able to formulate vengeance as he sought a terrible revenge on those that had killed his mate.
The story of Orca is generally considered to be a repeat of Jaws but it also has some elements of Moby Dick in it as well (such as an abnormally aggressive whale and the idea of revenge).