Wildlife includes those wild animals that are not domesticated and are not in captivity. At one time, the term referred only to those birds and mammals considered to be game animals. These animals were hunted for sport, such as the white-tailed deer, gray squirrel, cottontail rabbit, wild turkey, ruffed grouse, bobwhite quail, and wood duck. Game animals also included those furbearers that were trapped, including mink, muskrat, beaver, red fox, gray fox, and raccoon. Game animals were commonly categorized as upland game animals (deer, bear, rabbits, and squirrels), upland game birds (quail, turkey, and grouse), wetland game birds (ducks, geese, and woodcock), and wetland furbearers (beaver, mink, and muskrat).

In the past, wildlife traditionally did not include fish, which were considered to be a separate group. Fish historically were classified by biologists as either game fish or commercial fish, and little research and management effort were devoted to the nearly 100 other species of fish found in West Virginia waters. Game fish were those pursued for sport, such as the bass, trout, pike, and muskie, while commercial fish were those harvested for sale, such as buffalo, carp, channel catfish, and flathead catfish.

As biologists recognized the value of animals other than the game animals and game and commercial fish, the definition of wildlife was broadened to include the hundreds of species that were not hunted, trapped, or fished. During the 1970s, a distinction was made between game and nongame wildlife. The term "nongame wildlife" was used to describe those birds, mammals, and fish that were not hunted, trapped, or fished, including such animals as songbirds, hawks, owls, bats, mice, shrews, minnows, darters, and creek chubs. It was recognized that these animals had economic, scientific, and recreational value, as well as intrinsic worth. Efforts were initiated to preserve and manage nongame birds, mammals, and fish, which throughout West Virginia were much more numerous than were the game animals and game fish. There currently are approximately 50 species of game animals compared to 320 species of nongame animals, and approximately 25 species of game fish compared to more than 150 species of nongame fish.

By the 1980s, amphibians such as frogs, toads, and salamanders, plus reptiles such as lizards, snakes, and turtles, were also included with nongame wildlife. Thus, all vertebrates were considered to be wildlife, although fish were typically placed in a separate category of wildlife. The definition of wildlife broadened even more during the 1990s, and some of the larger and more appealing invertebrate species—butterflies, moths, mussels, and snails—were included.

An even broader definition of the term wildlife now in use encompasses not only all vertebrates, but also most invertebrate species, with small worms, insects, and spiders being included. The most liberal definition includes plants along with all kinds of animals. However, this definition has not yet received wide acceptance within the scientific community and is generally not accepted by the general public.

West Virginia's wildlife may be classified according to habitat. Wetland wildlife, forest wildlife, grassland wildlife, and wilderness wildlife are groups of animals that typically live in those specific habitats. Wetland wildlife include such animals as the beaver, muskrat, mink, wood duck, Canada goose, great-blue heron, snapping turtle, bullfrog, and spring peeper. Forest wildlife include the black bear, gray squirrel, flying squirrel, great horned owl, pileated woodpecker, and redback salamander. Grassland wildlife include the red fox, meadow vole, cottontail rabbit, meadowlark, song sparrow, kestrel, garter snake, smooth green snake, and box turtle. Wilderness wildlife in West Virginia are quite rare and include the mountain lion (now absent), golden eagle, and timber rattlesnake.

Most wildlife living in West Virginia are year-round residents, but a few—primarily birds—are seasonal visitors. All fish, amphibians, reptiles, and most mammals (other than a few bats) are year-round residents, while the majority of the more than 300 bird species known to occur in West Virginia are present only during certain months. Approximately 70 species of birds spend all 12 months in the Mountain State, while many others are seasonal residents or simply pass through while migrating. Examples of permanent residents are the mallard, Canada goose, red-tailed hawk, ruffed grouse, wild turkey, great-horned owl, pileated woodpecker, blue jay, crow, raven, chickadee, and cardinal. Among the nearly 100 seasonal residents that spend the summers nesting in West Virginia are the hummingbird, flycatchers, warblers, and thrushes. Fewer than 10 birds (cormorant, rough-legged hawk, and evening grosbeak) spend only the winters in West Virginia and typically nest farther north. Many wetland birds (including many waterfowl and shorebirds) are migratory visitors and may be observed only during the fall and spring months as they migrate between northern nesting grounds and southern wintering grounds. Most invertebrates are year-round residents although a few butterflies (notably the monarch) regularly migrate through West Virginia.

There have been significant changes in the species and numbers of resident wildlife in West Virginia. Some animals that were common prior to settlement—buffalo, elk, gray wolf, and passenger pigeon—had disappeared from the state by 1900. Other common wildlife present prior to the state's settlement had become so rare by 1900 that biologists predicted they would probably disappear during the 1900s. Some of these at-risk species were the beaver, river otter, mountain lion, wood duck, black bear, and fisher. As a result of reintroduction and management by the Wildlife Resources Section of the Division of Natural Resources, however, these species are all now more numerous than they were in 1900. The notable exception is the mountain lion, believed to have been extinct in the state since the 1930s.

Certain species of wildlife that faced extinction in West Virginia during the early 1900s have recovered to levels where they are now causing serious damage. The beaver, white-tailed deer, raccoon, and Canada goose are so abundant that their numbers need to be controlled. Others—black bear and wild turkey—are currently causing problems in some areas and could become serious pests in the future. The past century has demonstrated that wildlife are much more adaptable than biologists previously imagined, and if protected from hunting and harassment, most animals can live near humans. Bald eagles, osprey, and river otter were rare in West Virginia during the 20th century, but through adaptation most likely will become relatively common in West Virginia in the future. Perhaps the mountain lion will join them.

Some wildlife that historically were never known to occur in West Virginia are now found widely scattered throughout the state. For example, coyotes expanded their geographic range from the Southwest and are now present in every county in West Virginia. Another species, the elk, was once common in West Virginia, then lost, and now seems likely to return. The native herd in Pennsylvania is growing, and elk have been sighted in southwestern West Virginia, presumably from the herd introduced into Kentucky from the West. To encourage growth of the population, state wildlife officials began a multi-year stocking program in December 2016, bringing elk from eastern Kentucky to southwestern West Virginia.

Canada geese and bald eagles were rare visitors to West Virginia during the early 1900s, but were not known to nest here. Canada geese now nest in most counties, and bald eagles nest along the Potomac River and the Ohio River. Selected wildlife species were intentionally introduced into North America and have spread throughout West Virginia and most of the United States. Examples of these exotic species are the English sparrow, European starling, pigeon, and carp. Other wildlife species, such as the house mouse, Norway rat, black rat, and zebra mussel, were introduced accidentally into North America, and have become serious pests throughout West Virginia and other states. In contrast, a few exotic species have been intentionally released into West Virginia because of their sporting values as game animals or game fish and are now an integral and valued part of West Virginia's wildlife, including the brown trout, rainbow trout, ring-necked pheasant, and wild boar.

Another category of wildlife present in West Virginia is the group termed feral. These are animals that have returned to an untamed state following domestication; they are free-living and do not depend on humans for food or shelter. House cats are probably the most common feral animal in West Virginia, followed by feral dogs and goats.

In contrast to those species that have increased in numbers, many other wildlife species that were common during the 1800s have experienced serious declines throughout much of West Virginia. The numbers of spadefoot toads, upland chorus frogs, timber rattlesnakes, bobwhite quail, barn owls, whippoorwills, pink mucket pearly mussel, fanshell mussel, and clubshell mussel are now considerably lower than they were 100 years ago. The reasons for these declines are not fully understood, although loss of suitable habitat is the most likely factor.

The next 100 years will bring many noticeable changes to the wildlife of West Virginia. Some species will disappear and some will become rare, while others will become more abundant, and a few will certainly become pests. Regardless of the changes, the diversity of fascinating wildlife will be an integral part of West Virginia's natural history.