This is a list of mammals of Great Britain. 

The Great Britain mammal fauna is impoverished compared with that of continental Europe. This is because there was only a short time between the last ice age and the flooding of the land bridge between Britain and the rest of Europe. The list only has land species which crossed before the creation of the English Channel, and those later brought in by humans.

Native (indigenous) species have three possible definitions:
 a species which colonised the islands during the glacial retreat at the end of the last ice age (c.9500 years ago);
 a species that was present when the English Channel was created (c.8000 years ago);
 or, a species that was present in prehistory.

This list includes mammals from the small islands around Great Britain and the Channel Islands. There are no endemic mammal species in Great Britain, although four distinct subspecies of rodents have arisen on small islands.

Rodentia 
Rodents make up the largest order of mammals, with over 40 percent of mammalian species. They have two incisors in the upper and lower jaw which grow continuously and must be kept short by gnawing. Most rodents are small though the coypu (once introduced to Great Britain, but subsequently eradicated) can weigh up to 9 kg (15.5 lb).

Family: Castoridae (beavers)

Eurasian beaver  Castor fiber – Reintroduced

Family: Cricetidae (voles)

Bank vole  Myodes glareolus
Skomer vole  M. g. skomerensis
Field vole  Microtus agrestis
Common vole  M. arvalis
Orkney vole or Cuttick  M. a. orcadensis
Water vole  Arvicola terrestris

Family: Muridae (rats, mice and relatives)

Harvest mouse  Micromys minutus
Wood mouse  Apodemus sylvaticus
St Kilda field mouse  A. s. hirtensis
Yellow-necked mouse  A. flavicollis
House mouse  Mus musculus
St Kilda house mouse   M. m. muralis

Family: Gliridae (dormice)

Hazel dormouse  Muscardinus avellanarius

Family: Sciuridae (squirrels)

Red squirrel  Sciurus vulgaris

Lagomorpha 
The lagomorphs comprise two families, Leporidae (hares and rabbits), and Ochotonidae (pikas). Though they can resemble rodents, and were classified as a superfamily in that order until the early 20th century, they have since been considered a separate order. They differ from rodents in a number of physical characteristics, such as having four incisors in the upper jaw rather than two.

Family: Leporidae (hares and rabbits)

Mountain hare  Lepus timidus
Scottish mountain hare L. t. scoticus

Hedgehogs 

Superorder: Laurasiatheria
Order: Erinaceomorpha

The order Erinaceomorpha contains a single family, Erinaceidae, which comprise the hedgehogs and gymnures. The hedgehogs are easily recognised by their spines while gymnures look more like large rats.
European hedgehog  Erinaceus europaeus

Shrews and moles 
Superorder: Laurasiatheria
Order: Soricomorpha

The "shrew-forms" are insectivorous mammals. The shrews and soledons closely resemble mice while the moles are stout-bodied burrowers. 
European mole  Talpa europaea
Common shrew  Sorex araneus
Pygmy shrew  S. minutus
Water shrew  Neomys fodiens

Bats 
Superorder: Laurasiatheria
Order: Chiroptera

The bats' most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals in the world naturally capable of flight. Bat species account for about 20% of all mammals.

Greater horseshoe bat  Rhinolophus ferrumequinum
Lesser horseshoe bat  R. hipposideros
Greater mouse-eared bat  Myotis myotis – Vagrant
Whiskered bat  M. mystacinus
Brandt's bat  M. brandti
Natterer's bat  M. nattereri
Bechstein's bat  M. bechsteini
Daubenton's bat  M. daubentoni
Geoffroy's bat M. emarginatus
Alcathoe bat M. alcathoe
Parti-coloured bat  Vespertilio murinus – Vagrant
Serotine  Eptesicus serotinus
Northern bat  E. nilssoni – Vagrant
Common noctule  Nyctalus noctula
Leisler's bat or lesser noctule  N. leisleri
Hoary bat  Lasiurus cinereus – Vagrant
Common pipistrelle  Pipistrellus pipistrellus
Soprano pipistrelle  P. pygmaeus
Nathusius pipistrelle  P. nathusii
Kuhl's pipistrelle  P. kuhlii
Barbastelle  Barbastella barbastellus
Brown long-eared bat  Plecotus auritus
Grey long-eared bat  P. austriacus

Even-toed ungulates 
Superorder: Laurasiatheria
Order: Artiodactyla

The even-toed ungulates are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in perissodactyls. There are about 220 artiodactyl species, including many that are of great economic importance to humans.

Wild boar  Sus scrofa - Reintroduced
Feral goat  Capra aegagrus hircus - Bilberry goat
Sheep  Ovis orientalis aries - Soay sheep
Cattle  Bos primigenius taurus - Chillingham wild cattle
Scottish red deer  Cervus elaphus scoticus
Roe deer  Capreolus capreolus

Odd-toed ungulates 
Superorder: Laurasiatheria
Order: Perissodactyla

The odd-toed ungulates are browsing and grazing mammals. They are usually large to very large, and have relatively simple stomachs and a large middle toe.
Feral horse  Equus ferus caballus - Exmoor pony, Dartmoor pony

Carnivora 
Superorder: Laurasiatheria
Order: Carnivora

There are over 260 species of carnivorans, the majority of which feed primarily on meat. They have a characteristic skull shape and dentition. 

Domesticated dog Canis lupus familiaris
Red fox  Vulpes vulpes
Grey seal  Halichoerus grypus
Common seal  Phoca vitulina
Ringed seal  P. hispida – Vagrant
Bearded seal  Erignathus barbatus – Vagrant
Hooded seal  Cystophora cristatus – Vagrant
Harp seal  Pagophilus groenlandicus – Vagrant
Walrus  Odobenus rosmarus – Vagrant
Pine marten  Martes martes
Stoat (Ermine)  Mustela erminea
Least weasel  M. nivalis
European polecat  M. putorius
European otter  Lutra lutra
European badger  Meles meles
European wildcat  Felis silvestris silvestris
Domesticated cat Felis silvestris catus

Order: Cetacea

Whales 

The order Cetacea includes whales, dolphins and porpoises. They are the mammals most fully adapted to aquatic life with a spindle-shaped nearly hairless body, protected by a thick layer of blubber, and forelimbs and tail modified to provide propulsion underwater.

Suborder: Mysticeti
Family: Balaenidae
Genus: Eubalaena
 North Atlantic right whale Eubalaena glacialis EN
Family: Balaenopteridae
Subfamily: Balaenopterinae
Genus: Balaenoptera
 Fin whale Balaenoptera physalis
 Minke whale Balaenoptera acutorostrata LR/NT
 Sei whale Balaenoptera borealis
 Blue whale Balaenoptera musculus 
Genus: Megaptera
 Humpback whale Megaptera novaeangliae
Suborder: Odontoceti
Superfamily: Platanistoidea
Family: Monodontidae
Genus: Delphinapterus
 Beluga Delphinapterus leucas VU
Family: Phocoenidae
Genus: Phocoena
 Harbour porpoise Phocoena phocoena VU
Family: Physeteridae
Genus: Physeter
 Sperm whale Physeter macrocephalus VU
Family: Kogiidae
Genus: Kogia
 Pygmy sperm whale Kogia breviceps LR/LC
Family: Ziphidae
Genus: Ziphius
 Cuvier's beaked whale Ziphius cavirostris DD
Subfamily: Hyperoodontidae
Genus: Hyperoodon
 Northern bottlenose whale Hyperoodon ampullatus LR/CD
Genus: Mesoplodon
 Sowerby's beaked whale Mesoplodon bidens DD
 Gervais' beaked whale Mesoplodon europaeus DD
 True's beaked whale Mesoplodon mirus DD
Genus: Pseudorca
 False killer whale Pseudorca crassidens

Dolphins 

Family: Delphinidae (marine dolphins)
Genus: Delphis
Short-beaked common dolphin Delphinus delphis
Genus: Tursiops
 Common bottlenose dolphin Tursiops truncatus DD
Genus: Stenella
 Striped dolphin Stenella coeruleoalba LR/cd
Genus: Lagenorhynchus
 Atlantic white-sided dolphin Lagenorhynchus acutus LR/LC
 White-beaked dolphin Lagenorhynchus albirostris LR/LC
Genus: Grampus
 Risso's dolphin Grampus griseus DD

Introduced animals

Diprotodontia 
Though most marsupials make up a great part of the fauna in the Australian region, the red-necked wallaby has been introduced and a feral population is currently breeding on the island of Inchconnachan, and at Loch Lomond in Argyll and Bute, Scotland. A smaller group is present on the Isle of Man, and the species is locally extinct in the Peak District, in Cumbria, and at Ashdown Forest in East Sussex.

Family: Macropodidae (kangaroos, wallabies, and kin)

Red-necked wallaby Macropus rufogriseus - Introduced

Rodentia 
Rodents make up the largest order of mammals, with over 40 percent of mammalian species. They have two incisors in the upper and lower jaw which grow continuously and must be kept short by gnawing. Most rodents are small though the coypu (once introduced to Great Britain, but subsequently eradicated) can weigh up to 9 kg (15.5 lb).

Family: Muridae (rats, mice and relatives)

Black rat  Rattus rattus - Introduced
Brown rat  R. norvegicus - Introduced

Family: Gliridae (dormice)

Edible dormouse  Glis glis – Introduced

Family: Sciuridae (squirrels)

Grey squirrel  Sciurus carolinensis – Introduced

Lagomorpha 
The lagomorphs comprise two families, Leporidae (hares and rabbits), and Ochotonidae (pikas). Though they resemble rodents, and were classified as a superfamily in that order until the early 20th century, they have since been put in a separate order. They differ from rodents in a number of physical characteristics, such as having four incisors in the upper jaw rather than two.

Family: Leporidae (hares and rabbits)

Mountain hare  Lepus timidus
Irish hare L. t. hibernicus – Introduced Isle of Mull
European hare  L. europaeus – Possibly introduced
European rabbit  Oryctolagus cuniculus – Introduced

Shrews and moles 
Superorder: Laurasiatheria
Order: Soricomorpha

The "shrew-forms" are insectivorous mammals. The shrews and soledons closely resemble mice while the moles are stout-bodied burrowers.
Greater white-toothed shrew  Crocidura russula – Likely introduced, Channel Islands only
Lesser white-toothed shrew  C. suaveolens – Likely introduced, Isles of Scilly and Channel Islands only

Even-toed ungulates 
Superorder: Laurasiatheria
Order: Artiodactyla

The even-toed ungulates are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in perissodactyls. There are about 220 artiodactyl species, including many that are of great economic importance to humans.
Sika deer  C. nippon – Introduced
Fallow deer  Dama dama - Introduced
Reeves's muntjac  Muntiacus reevesi – Introduced
Water deer  Hydropotes inermis – Introduced

Carnivora 
Superorder: Laurasiatheria
Order: Carnivora

American mink  M. vison – Introduced

References

Other websites
A Review of British Mammals, 1995  (PDF format)
The Mammal Society: Mammals of the British Isles
Discuss UK wildlife 

Mammals of Europe
Great Britain
Lists of mammals