This article covers a licensed crossover event that has been deemed non-canon by either the author or the Alien vs. Predator licensees, and thus should not be taken as a part of the "real" Alien vs. Predator universe.
The Killer Croc Xenomorph was a hybrid that appeared only in Batman/Aliens Vol. 2. Its creation was the result of biomatter taken from Killer Croc.
Unlike the other hybrids created by Dr. Fortune to whom she had added her DNA that were loyal and controlled by her, the Killer Croc hybrid hadn't had her DNA added to it and was uncontrollable, murdering its 'creator' with a Headbite upon encountering her.