Aliens are a mainstay in many forms of fiction, and comics are no exception. This page lists aliens from major comic companies.
Key: Alien (Notes/Description) - Notable members of that race
Darkhorse
Aliens (Xenomorphs)
DC
Coluans - Brainiac
Czarnians (Only one remaining) - Lobo
Kryptonians - Superman, Supergirl, Power Girl
Green Martians - Martian Manhunter
New Gods - Darkseid, High Father
Tamaranians - Starfire, Blackfire
Thanagarians - Hawkman, Hawkwoman
White Martians - Miss Martian
Marvel
Badoon - Brother Royal
Brood - No-Name
Celestials
Centaurians - Yondu
Eternals - Thanos, Starfox
Ethereals - Stardust
Galadorians - ROM
Inhumans (considered alien but terrestrial in origin) - Black Bolt, Crystal, Medusa, Karnak
Korbinites - Beta Ray Bill
Kronans - Korg
Kymellians - Kofi
Landlaks - Terrax
Luphomoids - Nebula
Makluans / Axonn-Karr - Fin Fang Foom
Mephitisoids - Hepzibah
N'Garai
Phalanx
Plodex - Marrina
Poppupians - Impossible Man
Rigellians - Tana Nile
Saurids - Ch'od
Shi'ar (Shi'ar includes many different aliens) - Lilandra, Deathbird, Deathcry, Gladiator, Cerise
Skrulls (shape shifters) - Super Skrull
Space Phantoms
Spartoi - Starlord
Symbiotes - Venom, Carnage
Time Lords - Doctor Who
The Watchers - Uatu
Xandarians - Air-Walker
Zenn-Lavians - Silver Surfer, Shalla Bal
Zen Whoberi - Gamora
Image
Unopan - Allen
Viltrumites - Invincible, Omniman
Wildstorm
Daemonites - Helspont
D'rhan
Kherubim - Mr. Majestic, Zealot, Emp
S'rynn
Thundarians - Lion-O and other Thunder Cats
Vigil
Top Cow
Batai - Ansh'r, Lilith, Lorelei.
Hunters of Tao - Lord Hunter, Spasm, Torpid.
Mekadom -
Theran - Alia Sparrow, Crucifer.
Avatar
Asgard - Thor
Nox -
Ancients - Oma
Wraith -
