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- Labeo fisheri — Green Labeo, Mountain Labeo
- Labeo lankae
- Labeo mesops — Tana Labeo
- Labeo seeberi — Clanwilliam Sandfish
- Labidura herculeana — Saint Helena Giant Earwig
- Lacerta clarkorum
- Lacerta fraasii — Fraas' Lizard
- Lacerta kulzeri
- Laevicaulis haroldi — Purcell's hunter slug
- Laminella sanguinea
- Lamottemys okuensis — Mt. Oku Rat
- Lampedusa melitensis
- Lamprocystis hahajimana
- Lamprologus kungweensis
- Lamprophis geometricus — Seychelles House Snake
- Lampsilis abrupta — Pink mucket
- Lampsilis altilis — Fine-lined pocketbook
- Lampsilis cariosa — Yellow lampmussel
- Lampsilis higginsii — Higgins' eye pearly mussel
- Lampsilis powellii — Arkansas fatmucket
- Lampsilis rafinesqueana — Neosho mucket, Neosho pearly mussel
- Lampsilis streckeri — Speckled pocketbook
- Lampsilis virescens — Alabama lamp naiad, Alabama lamp pearly mussel, Alabama lampmussel
- Laniarius amboimensis — Gabela Bush-shrike
- Laniarius brauni — Orange-breasted Bush-shrike
- Laniarius liberatus — Bulo Burti Boubou
- Lanistes alexandri
- Lanistes farleri
- Lanistes nasutus
- Lanistes neritoides
- Lanistes nyssanus
- Lanistes solidus
- Lanistes stuhlmanni
- Lanius newtoni — São Tomé Fiscal
- Lantzia carinata
- Larus bulleri — Black-billed Gull
- Lasiorhinus krefftii — Northern Hairy-nosed Wombat, Queensland Hairy-nosed Wombat
- Lasmigona decorata — Carolina heelsplitter
- Laterallus levraudi — Rusty-flanked Crake
- Laterallus tuerosi — Junín Rail
- Lates angustifrons — Tanganyika lates
- Lates macrophthalmus — Albert lates
- Lates microlepis — Forktail lates
- Lathamus discolor — Swift Parrot
- Latidens salimalii — Salim Ali's Fruit Bat
- Latimeria chalumnae — Coelacanth, Gombessa
- Leiopelma archeyi — Archey's Frog
- Leiopelma hamiltoni — Hamilton's Frog, Stephens Island Frog
- Leiostyla abbreviata — Madeiran land snail
- Leiostyla cassida — Madeiran land snail
- Leiostyla gibba — Madeiran land snail
- Leiostyla heterodon
- Leiostyla simulator
- Lemiox rimosus — Birdwing pearlymussel
- Leontopithecus caissara — Black-faced Lion Tamarin
- Leontopithecus chrysomelas — Golden-headed Lion Tamarin
- Leontopithecus chrysopygus — Black Lion Tamarin, Golden-rumped Lion Tamarin
- Leontopithecus rosalia — Golden Lion Tamarin
- Leopoldamys neilli — Neill's Long-tailed Giant Rat
- Lepidoblepharis montecanoensis — Paraguanan Ground Gecko
- Lepidocephalichthys jonklaasi — Spotted Loach
- Lepidochelys kempii — Atlantic Ridley, Gulf Ridley, Kemp's Ridley, Mexican Ridley
- Lepidochelys olivacea — Olive Ridley, Pacific Ridley
- Lepidochrysops lotana
- Lepidomeda albivallis — White River spinedace
- Lepidopyga lilliae — Sapphire-bellied Hummingbird
- Lepidurus packardi
- Leporillus conditor — Greater Stick-nest Rat, House-building Rat
- Leptachatina lepida
- Leptasthenura xenothorax — White-browed Tit-spinetail
- Leptaxis caldeirarum
- Leptaxis vetusa
- Leptaxis wollastoni
- Leptobrachella palmata
- Leptodactylodon axillaris
- Leptodactylodon erythrogaster
- Leptodactylodon mertensi
- Leptodactylodon ornatus
- Leptodactylodon perreti
- Leptodactylodon stevarti
- Leptodactylodon wildi
- Leptodactylus dominicensis — Hispaniolan Ditch Frog
- Leptodactylus fallax — Giant Ditch Frog, Mountain Chicken
- Leptodactylus magistris
- Leptodactylus silvanimbus
- Leptodon forbesi — White-collared Kite
- Leptogomphus yayeyamensis
- Leptolalax alpinus
- Leptomys elegans — Long-footed Water Rat
- Leptomys signatus — Fly River Water Rat
- Leptonycteris nivalis — Greater Long-nosed Bat, Mexican Long-nosed Bat
- Leptopelis karissimbensis
- Leptopelis susanae
- Leptopelis xenodactylus — Long-toed Tree Frog
- Leptophryne cruentata — Bleeding toad, Fire toad
- Leptoptilos dubius — Greater Adjutant
- Leptotila conoveri — Tolima Dove
- Leptotila wellsi — Grenada Dove
- Leptoxis melanoidus — Black mudalia
- Lepus flavigularis — Tehuantepec Hare, Tehuantepec Jack Rabbit, Tehuantepec Jackrabbit
- Lerista allanae — Allan's Lerista
- Lerista vittata — Mount Cooper Striped Lerista
- Lethenteron zanandreai — Lombardy Brook Lamprey
- Lethrinops macracanthus
- Lethrinops micrentodon
- Lethrinops microdon
- Lethrinops stridae
- Leuchocharis pancheri
- Leucocephalon yuwonoi — Sulawesi Forest Turtle
- Leucopeza semperi — Semper's Warbler
- Leucopsar rothschildi — Bali Starling
- Leucopternis occidentalis — Grey-backed Hawk
- Leucoraja melitensis — Maltese skate
- Lexingtonia subplana
- Libellula angelina
- Liberiictis kuhni — Liberian Mongoose
- Limnonectes arathooni
- Limnonectes microtympanum
- Limnonectes namiyei — Namiye's Frog
- Limnonectes nitidus
- Lineatriton lineolus
- Lineatriton orchileucos
- Lineatriton orchimelas
- Liobagrus nigricauda
- Liophis cursor
- Liophis ornatus — St Lucia Racer
- Liophis perfuscus — Barbados Racer
- Lipaugus weberi — Chestnut-capped Piha
- Lipochromis maxillaris
- Lipochromis sp. nov. 'backflash cryptodon'
- Lipochromis sp. nov. 'small obesoid'
- Lipochromis sp. nov. 'black cryptodon'
- Lipochromis sp. nov. 'parvidens-like'
- Lipotes vexillifer — Baiji, Changjiang Dolphin, Chinese Lake Dolphin, White Flag Dolphin, Whitefin Dolphin, Yangtze River Dolphin
- Lirceus usdagalun — Lee County Cave Isopod
- Lithochromis rubripinnis
- Lithochromis rufus
- Lithochromis xanthopteryx
- Litoria booroolongensis — Booroolong Frog
- Litoria brevipalmata — Green-thighed Frog
- Litoria castanea — Yellow-spotted Tree Frog
- Litoria cooloolensis — Cooloola Sedgefrog, Cooloola Tree Frog
- Litoria lorica — Armoured Frog, Armoured Mistfrog
- Litoria nannotis — Torrent Tree Frog, Waterfall Frog
- Litoria nyakalensis — Mountain Mistfrog, Nyakala Frog
- Litoria piperata — Peppered Tree Frog
- Litoria raniformis — Green and Gold Frog, Growling Grass Frog, Southern Bell Frog, Warty Bell Frog
- Litoria rheocola — Common Mist Frog
- Litoria spenceri — Spencer's River Tree Frog, Spotted Frog, Spotted Treefrog
- Liza luciae — Saint Lucia mullet
- Lobaunia danubialis
- Loddigesia mirabilis — Marvellous Spatuletail
- Lokia coryndoni
- Lontra felina — Marine Otter, Sea Cat, Chungungo
- Lontra provocax — Huillin, Southern River Otter
- Lophornis brachylophus — Short-crested Coquette
- Lophura edwardsi — Edwards's Pheasant
- Lophura hatinhensis — Vietnamese Pheasant
- Loriculus catamene — Sangihe Hanging-parrot
- Loriculus flosculus — Flores Hanging-parrot
- Loris tardigradus — Slender Loris
- Lorius garrulus — Chattering Lory
- Louisea edeaensis
- Loxia megaplaga — Hispaniolan Crossbill
- Loxioides bailleui — Palila
- Loxops caeruleirostris — 'Akeke'e
- Loxops coccineus — 'Akepa
- Lucania interioris
- Lutilodix imitratrix
- Lycaon pictus — African Wild Dog, Cape Hunting Dog, Wild Dog
- Lyciasalamandra antalyana
- Lyciasalamandra atifi
- Lyciasalamandra billae
- Lyciasalamandra fazilae
- Lyciasalamandra flavimembris
- Lyciasalamandra luschani — Luschan's Salamander, Lycian Salamander
- Lycognathophis seychellensis — Seychelles Wolf Snake
- Lynx pardinus — Iberian Lynx, Pardel Lynx, Spanish Lynx
Read more about this topic: IUCN Red List Endangered Animal Species