ANDREENIDS / ANDRINOS

The Andreenids are an insectoid species indigenous to planet Eternia. Their body is roughly that of a winged humanoid. Although individuals have their own personnality, they follow a hive social structure. Distrustful and proud, they keep their contacts with other species minimal. They are not known to use any advanced technology.
Source: He-Man and the Masters of the Universe.

EVIL HORDE

The Evil Horde is a spacefaring agressive power bent on conquest lead by a mysterious entity known as Horde Prime.
The few high ranking officers of the Horde, humanoid for the most part, all seem to be unique specimens, with might hint at some artificial origins or manipulations - either genetic or mystic, of the individuals. All are known to have special powers and often use magic. The bulk of the Horde's Power is composed of mass-produced humanoid robots.
Horde Prime and the Horde troopers bear a lot similarities, with the Beast and its army seen in the film Krull.

SNAKE MEN / REPTONS

Snake Men are a species of humanoid saurians who developed as an agressive spacefaring civilisation. They invaded planet Eternia in the distant past and were defeated. There now remains only a handful of them and most of them have devolved into the more peaceful reptons.

ETERNIANS / ETHERIANS

Eternians and etherians are humanoid species ressembling normal humans and genetically compatible with them. It has been hinted that they might be descendants from humans of the future.
They are the dominant lifeform on both Eternia and Etheria, sister planets orbiting a yellow sun whose exact spatial location remains unknown, although it has been hinted that it might be inside a space-time singularity, wether a junction of alternate universes or a pocket dimension caused by the presence, for a long time, of the Starseed at its core, a spark left over from the creation of the universe.
Some kind of wormhole exists linking Eternia's system to the Solar system and two space expedition have been known to fall through it.
Eternia is quite earthlike and has large bodies of water. It is separated into two very distinctive regions, the light and a dark hemisphere.
Eternians developped a technologically very advanced civilisation that has, for msot of it, regressed to a much more barbaristic state. Although some very advanced technology is still in use on the planet, it cohabits with magical science.
Apart from the dominant humanoid lifeform, the planet features an incredible variety of lifeforms, from monsters to sentient races.