1) Bipedal near-humans
These are aliens who appear to closely resemble us humans. But perhaps for their skin colour, a few bulges, minor alterations to physical features and more or fewer toes and fingers, etc. these guys are like us. These include: Critical Mass Games’ Mercs, Kaamados and Praesentia; Ground Zero Games’ Kra’Vak and Alien Mercs and Greys; Rebel Miniatures' Kurgens, and Grey Aliens amongst others; 15mm.co.uk’s Grey Aliens, Shia Khan, Octopods, Ghoulani, Froogs and Zidhe, etc; Blue Moon aliens including the Arlocks, Shivan Sisterhood, Aquans, etc; Eureka Miniatures' Ventaurians; Khurasan Miniatures’ Chewk and Vacation Aliens and; Zombie Smith’s Quar.
2) Anthropomorphic aliens
These are Earth animals that appear to have been “uplifted” and now run around blasting up the galaxy like a bunch of naked apes with advanced tech. These include: Khurasan Miniatures’ Felid, Garn, Ursid, Karkarine, Myzontid and Orca; 15mm.co.uk's Draccians; Critical Mass Games' Protolene Khanates and Astagar (snakemen); Ground Zero Games’ Crusties; Stan Johansen's Blarad; ArtCrime Production's Hadai; Irregular Miniature's Reptilians and Space Goatmen; and Traveller War Hounds of Sirius, Car Leonis and Dracos produced by RAFM.
3) Bug life
Similar to anthropomorphic aliens (perhaps a subclasification?), there is alien life out there that has a passing resemblance to Earth’s insect life. These include: Ground Zero Games’ Ixx; QRF Alien Bipeds; Khurasan Miniatures’ Vespulid and Space Demons (possibly) amongst others; Battlestation's Zoallans; Spriggan Miniatures’ Spugs, Brigade Models' Cimexians; Highlander Studios' Space Bugs; and Micro Panzer’s Raivaui Swarm.
4) Intergalactic weirdness
At the weirder (more alien!?!) end of the spectrum there is: Khurasan Miniatures’ Vornids (triffids / ambulatory plants), Cnidarian, and the wonderfully alien Molch extensions and emissaries; Moonfleet (ex Peter Pig) Phugs; Battlestation's Canosians, Xeloxians, Silicoids, amongst others, and; 15mm.co.uk’s Creegan Doom Spores and various aliens in the SHM Range.
You may disagree with our classifications and we may have missed a few 15mm aliens, but the Dropship Crew are interested to know if you have a favourite 'type' of alien and more generally what kind of aliens you would like to see in the future from 15mm sci fi manufacturers!