List of mammals of Christmas Island
This is a list of the mammal species recorded on Christmas Island. The island had five native and endemic land mammal species, of which four are now presumed to be extinct. In addition, five exotic wild mammals have been introduced to Christmas Island.
Carnivora
Introduced cats and dogs are a threat to native wildlife on Christmas Island and can carry potentially dangerous pathogens, such as Leptospira. In 2014, the Australian Government announced a $500,000 investment to help eradicate stray and feral cats on the island, with the aim of complete eradication by 2020. As of 2016, all pet cats on Christmas Island have been registered and de-sexed and no further cats will be permitted onto the island.| Name | Species authority | Order | Family | Notes |
| Feral cat | Felis catus Linnaeus, 1758 | Carnivora | Felidae | introduced |
| Feral dog | Canis lupus familiaris Linnaeus, 1758 | Carnivora | Canidae | introduced |
Chiroptera
Christmas Island was once home to two native bat species, of which only one is extant. The Christmas Island pipistrelle was endemic to the island until 2009, when the last individual was recorded. In 2016, the species was assessed as extinct by the International Union for the Conservation of Nature. The remaining native bat species Pteropus natalis is classified as critically endangered.| Name | Species authority | Order | Family | Notes | Red List |
| Christmas Island pipistrelle | Pipistrellus murrayi Andrews, 1900 | Chiroptera | Vespertilionidae | was endemic - last reported in 2009 | |
| Christmas Island flying fox | Pteropus natalis Thomas, 1887 | Chiroptera | Pteropodidae | endemic |
Eulipotyphla
The Christmas Island shrew, once abundant on the island, has been very rare since the early twentieth century. Since 1909, only four confirmed individuals have been recorded: two in 1958, and two in 1985.| Name | Species authority | Order | Family | Notes | Red List |
| Christmas Island shrew | Crocidura trichura Dobson, 1889 | Eulipotyphla | Soricidae | endemic - possibly extinct - last observed in 1985 |
Rodentia
At the time of human settlement, Christmas Island hosted two endemic rodents, the bulldog rat and Maclear's rat. However, both species were extinct by 1908. There is evidence that black rats, introduced to the island in 1899, carried the infectious parasite Trypanosoma lewisi, which was fatal to the native rodents.| Name | Species authority | Order | Family | Notes | Red List |
| Maclear's rat | Rattus macleari Thomas, 1888 | Rodentia | Muridae | endemic - extinct | |
| Bulldog rat | Rattus nativitatis Thomas, 1888 | Rodentia | Muridae | endemic - extinct | |
| Black rat | Rattus rattus Linnaeus, 1758 | Rodentia | Muridae | introduced in 1899 | |
| House mouse | Mus musculus Linnaeus, 1758 | Rodentia | Muridae | introduced | |
| Pacific rat | Rattus exulans Peale, 1848 | Rodentia | Muridae | introduced |
Cetacea
| Name | Species authority | Order | Family | Notes | Red List |
| Humpback whale | Megaptera novaeangliae Gray, 1846 | Cetacea | Balaenopteridae | native migrant | |
| Blue or pygmy blue whales | Balaenoptera musculus intermedia Linnaeus, 1758 | Cetacea | Balaenoptiidae | possible migrant | |
| Southern fin whale | Balaenoptera physalus quoyi Linnaeus, 1758 | Cetacea | Balaenoptiidae | native migrant or resident | |
| Sei whale | Balaenoptera borealis schlegelii Linnaeus, 1758 | Cetacea | Balaenoptiidae | native migrant | |
| Bryde's whale | Balaenoptera brydei Linnaeus, 1758 | Cetacea | Balaenoptiidae | native migrant or resident | |
| Antarctic minke whale | Balaenoptera bonaerensis Linnaeus, 1758 | Cetacea | Physeteridae | native migrant | |
| Sperm whale | Physeter macrocephalus Linnaeus, 1758 | Cetacea | Physeteridae | native migrant or resident | |
| Short-finned pilot whale | Globicephala macrorhynchus Gray, 1846 | Cetacea | Globicephala | native migrant or resident | |
| Killer whale | Orcinus orca Linnaeus, 1758 | Cetacea | Delphinidae | native migrant or resident | |
| Spinner dolphin | Stenella longirostris Gray, 1828 | Cetacea | Delphinidae | native migrant or resident | |
| Short-beaked common dolphin | Delphinus delphis Linnaeus, 1758 | Cetacea | Delphinidae | native migrant or resident | |
| Common bottlenose dolphin | Tursiops truncatus Montagu, 1821 | Cetacea | Delphinidae | possible migrant |
Sirenia
| Name | Species authority | Order | Family | Notes | Red List |
| Dugong | Dugong dugon Lacépède, 1799 | Sirenia | Dugongidae | possible vagrant |