| Name | Source | Type |
|---|
| L1Z1X Mindnet | Twilight Imperium | cybernetic-organic hybrids |
| Lagomorphic Humanoids | Adventure Time: Distant Lands | Rabbit-like humanoids: Y5, Y5’ Dad and KS-2 |
| Lallorans | DC Comics' Legion of Super-Heroes | |
| Lance Corporal Dororo | Sgt. Frog | |
| Large Nostril People of Boodie-Nen | Invader Zim | |
| Lavos | Square-Enix's Chrono Trigger | planetary parasite |
| Laxidasians | Marvel Comics | humanoid |
| Lectroids | The Adventures of Buckaroo Banzai Across the Eighth Dimension | |
| Leerans | K. A. Applegate's Animorphs | A yellow amphibian species with tentacles for arms that resembles a manta ray or frog. They live in the vast oceans on their homeworld, Leera, which has only one small continent of land (originally, Leerans needed to go on land to mate, but technology has made that unnecessary). Leerans have advanced psychic powers, which make them very desirable Yeerk hosts. |
| Lekgolo | Halo | |
| Legislators | Captive State | |
| Leoniders | Noon Universe | humanoid |
| Lepidopterran | Ben 10 | Lepidopterrans come in two variations depending on the series. In the Original series, they resemble a combination of dragonflies, hornets, and butterflies, and are equipped with sharp stingers on their tails and four penduculated eyes on the sides of their heads. In the reboot, however, they more closely resemble humanoid dragonflies, complete with antenna and compound eyes. Both versions can spray foul smelling slime and fly at high speeds, but are frail and not particularly strong. |
| Leviathan | Farscape | bio-mechanoid (artificially engineered, living sentient spaceship. Capable of natural procreation) |
| Life Fibers | Kill la Kill | Thread-like creatures that can be merged with either clothing or human beings. Appear to be a hostile hive-mind with the ulterior motive of planetary destruction. |
| Liir | Sword of the Stars | |
| Limax | Ben 10 | Gelatinous, shapeshifting creatures who are carnivorous in nature, more specifically preying on elderly humans. They are fond of high levels of heat, but are weak to and afraid of water. |
| Lipul | Star Trek | |
| Lithians | James Blish's A Case of Conscience | |
| Little Guys | 2300 AD | |
| Livrai | Joe Haldeman's Mindbridge | |
| Lk (fungi type alien) | Star Control 3 | |
| Llorn | The Haunted Stars | Neckless bipeds who veil themselves and their spacecraft in shadow. Soft-spoken but powerful. Feared on the planet Ryn, whose empire they destroyed 30 thousand years ago. |
| Loboan | Ben 10 | Aliens resembling werewolves hailing from the moon Luna Lobo, they are very vicious hunters. Alongside enhanced strength, speed, hearing, and agility, they can see in the dark and unleash powerful sonic howls. |
| Lobster Men | X-COM: Terror from the Deep | |
| Locust | Gears of War | aliens that originate from beneath the surface of the Earth. Intent on destroying humanity. |
| Logrians | The History of the Galaxy series | |
| Lohvo | Sluggy Freelance | |
| Lombaxes | Ratchet & Clank | |
| Loomi | Space Patrol | creatures inhabiting Jupiter with heat-retaining skins |
| Loric | Lorien Legacies | A peaceful race from the planet Lorien, who were almost wiped out by another alien race, the Mogadorians. They currently reside on Earth. |
| Lorwardians | Kim Possible | humanoid |
| Lucratians | Utopia | |
| Lumas | Super Mario Galaxy , Super Mario Galaxy 2 | |
| Luminoth | Metroid Prime 2: Echoes | peaceful race that worships "Light of Aether." Fight against Ing for control of homeworld. Only a single Luminoth is ever encountered, known as U-Mos. |
| Lunarians | Final Fantasy IV | (月の民, Tsuki no tami?, lit. "Moon People"); light-haired humanoid beings from the Moon. |
| Lunarian | Touhou Project | humanoid alien race that lives on the Earth's moon. Notable members of the race would be Kaguya Houraisan and Eirin Yagokoro. |
| Lunatone | Pokémon | |
| Lurian | Star Trek | |
| Lurmans | Doctor Who | Humanoid |
| Luxans | Farscape | humanoid |
| Ly-Cilph | The Night's Dawn Trilogy | |
| Lycocians | Star Trek | |
| Lyrans | Star Fleet Universe | |