A pack hunter is a predator belonging to the animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

 kingdom, which has evolved to hunt its prey by working together with other members of its species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. Normally, such animals are closely related. The most commonly known pack hunter is the Gray Wolf

Gray Wolf

The gray wolf , also known as the wolf, is the largest extant wild member of the Canidae family...

, the ancestor of all breeds of domesticated dog

Dog

The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

s. This pack-hunting history is thought to be the main conduit through which humans have been able to form a mutual relationship with dogs (that is, domestication

Domestication

Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...

), as both species are highly social and inter-dependent. Humans and their closest-living relatives chimpanzee

Chimpanzee

Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s are themselves pack hunters even without aid of other species. Other pack hunters include simple arthropods such as ants, highly intelligent mammals such as dolphins, orcas, lions, and hyenas, a few bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s such as the Harris Hawk, and occasionally crocodiles. There is a possibility that some non-avian theropod dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s displayed pack behavior as well.

When wolves hunt a Moose or Elk, it sometimes takes to deep water to avoid the pack. A wolf response to this behavior is that the pack rests with one or two wolves annoying the prey until it gets fatigued.
The organization of wolf packs includes Alpha wolves which eat first from a kill and which produce most wolf pups.

A social animal that always hunts singly such as the domestic cat

Cat

The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...

is not a pack hunter.