Grineer

"Vast in numbers, the Grineer have expanded their vile empire from Earth outward to all sectors of the solar system. Once the Grineer rediscovered cloning technology, they seized control of Earth through sheer numbers. While they may be at the height of power, the Grineer army is in bodily decay and their features are increasingly primitive as a result of continuous cloning. As such, the Grineer are forced to use technology as a crutch for their genetic deterioration. An ideology of hate and discrimination towards the Tenno continues to drive the Grineer forward in the face of inevitable dissolution."

- Warframe Official Website

The Grineer are the first enemies encountered by the player, and use basic tactics and weaponry. Their standard forces are made up of basic cloned marines. While fairly weak individually, they are more of a threat in groups. Specialty troops use more advanced techniques. They are the last remnants of the human race degraded from cloning, other than the Tenno. When Earth is selected it states that it is the homeworld of the "Oppressive Grineer Empire".

Light
Light Grineer units emphasize in melee combat over ranged.

Medium
Medium troops make up the bulk of the Grineer army. They are armored and carry ranged weapons. They are not particularly dangerous when alone, but in groups they can pose a serious threat.

Heavy
These units are the strongest and toughest of the Grineer. They all have slow regenerating personal shields. Apart from the Grineer Commander, these units don't take advantage of cover. Heavy Grineer cannot seem to retaliate while under attack, showing a vulnerability to status effects; therefore it is possible to dispatch lone Heavy units easily with sustained firepower. Also, their shields will only regenerate if unbroken; once it is completely depleted, it can't be replenished. All Heavy Grineer make use of crowd controlling abilities. The Heavy Gunner, Bombard and Napalm release a short range shockwave to knock players down and backwards when first approached at close range. This ability has a long cooldown, so normal melee is possible once the shockwave has been drawn out. Commanders use Switch Teleport from a relatively long range and through cover.

Utility
The utility enemies of the Grineer are dangerous in their own right. The Nervo, for example, is deployed by Seekers and can completely incapacitate a player in multiplayer games.

Captain Vor
Captain Vor is the final boss in the Mercury system and the first boss that players will meet. He can be found on Tolstoj. He will drop the Cronus blueprints on death. He also drops Morphics.

Councilor Vay Hek
Councilor Vay Hek is the final boss in the Earth system. He is found at Everest. He has a chance of dropping one of the following on death: Trinity Helmet, Trinity Chassis, Trinity Systems blueprints, as well as Neurodes, and Orokin Cells.

General Sargas Ruk
General Sargas Ruk is the final boss of the Saturn system. He can be found on Tethys. He has a possibility of dropping one of the following on death: Ember Helmet, Ember Chassis and Ember Systems blueprints, and the Orokin Cell.

Kela De Thaym
Kela De Thaym is the boss of Sedna. She can be found on '''Merrow. ''' She has a possibility of dropping one of the following on death: Saryn Helmet,Saryn Chassis or Saryn Systems blueprints.

Lieutenant Lech Kril
Lieutenant Lech Kril is the final boss of Ceres. He can be found on Exta. He has a possibility of dropping one of the following upon death: Frost Helmet, Frost Chassis and Frost Systems blueprints, as well as the Orokin Cell.

Tyl Regor
Tyl Regor is the final boss of the Uranus system. He can be found on Titania. He has a possibility of dropping one of the following on death: Ash Helmet, Ash Chassis and Ash Systems blueprints, as well as Gallium.