Mammalia → Chiroptera → Microchiroptera → Vespertilionidae → Vespertilioninae → Vespertilionini
, Ichneumia
, Ichthyomys
, Ictidomys
- Ictonyx libycus (Hemprich and Ehrenberg, 1833)
- Ictonyx libycus libycus (Hemprich and Ehrenberg, 1833)
- Ictonyx libycus multivittatus (Wagner, 1841)
- Ictonyx libycus oralis (Thomas and Hinton, 1920)
- Ictonyx libycus rothschildi (Thomas and Hinton, 1920)
- Ictonyx striatus (Perry, 1810)
- Ictonyx striatus albescens Heller, 1913
- Ictonyx striatus arenarius Roberts, 1924
- Ictonyx striatus elgonis Granvik, 1924
- Ictonyx striatus erythreae de Winton, 1898
- Ictonyx striatus ghansiensis Roberts, 1932
- Ictonyx striatus giganteus Roberts, 1932
- Ictonyx striatus intermedius Anderson and de Winton, 1902
- Ictonyx striatus kalaharicus Roberts, 1932
- Ictonyx striatus lancasteri Roberts, 1932
- Ictonyx striatus limpopoensis Roberts, 1917
- Ictonyx striatus maximus Roberts, 1924
- Ictonyx striatus obscuratus de Beaux, 1924
- Ictonyx striatus orangiae Roberts, 1924
- Ictonyx striatus ovamboensis Roberts, 1951
- Ictonyx striatus pretoriae Roberts, 1924
- Ictonyx striatus senegalensis (J. B. Fischer, 1829)
- Ictonyx striatus shoae Thomas, 1906
- Ictonyx striatus shortridgei Roberts, 1932
- Ictonyx striatus striatus (Perry, 1810)
Mammalia → Carnivora → Mustelidae
, Idionycteris
, Idiurus
- †Indarctos anthracitis Weithofer 1888
- †Indarctos arctoides Deperet 1895
- †Indarctos atticus Weithofer 1888
- †Indarctos nevadensis Macdonald 1959
- †Indarctos oregonensis Merriam 1925
- †Indarctos salmontanus Pilgrim 1913
- †Indarctos vireti Villalta and Crusafont 1943
- †Indarctos zdanskyi Qiu and Tedford 2003
Mammalia → Carnivora → Caniformia → Ursidae → Ursinae → Ursavini
, Indopacetus
, Indri
Mammalia → Perissodactyla → Tapiromorpha → Ceratomorpha → Rhinocerotoidea
- †Indricotherium qujingensis Tang 1978
- †Indricotherium transouralicum Pavlova 1922
Animalia → Chordata → Mammalia → Perissodactyla → Indricotheriidae
, Indridae
, Inia
, Iniidae
, Iomys
, Irenomys
, Isolobodon
, Isoodon
, Isothrix
, Isthmomys