Orokin

The Orokin are a precursor race that ruled over the Solar System for a period of time. During what was known as the Orokin Era, they built technological masterpieces that rival even present day technology. Their descendants are the Tenno, but more information as to how or why is still not known. Although there is almost no information about the Orokin race, their technology, or their disappearance, they play a crucial part in the universe of Warframe.

Orokin Void
The Void is a secret location which houses the Orokin towers. These towers are equipped with many defense mechanisms, including lethal laser traps and neural sentries used to "corrupt" intruders, forcing them to fight for the tower's defense. The towers exist in a space outside of real space requiring keys to attune to the tower and enter them.

Corrupted
The Corrupted are Orokin controlled enemies found in Orokin Void levels. These enemies consist of various normal Grineer, Corpus and Infested infantry, but are implanted with an unknown mind-control device that allows the Orokin's Neural Sentry to control them. These enemies appear and behave similarly to their normal counterparts. They are the sole enemy type that the player will encounter upon entering an Orokin Tower mission.

Technocyte Virus
During a war with what were known as the "Sentients" the Orokin created the Technocyte Virus as a way to combat them. Very little information remains on what their goals may have been, but this shows the Orokin had a mastery over organic and technological aspects.

Trivia

 * The Corpus, according to the Lore, are hellbent on gathering Orokin technology and relevant findings in order to harness their power and sell them on the market. Their goals were the primary cause of certain events, namely The Gradivus Dilemma and Operation Oxium Espionage.
 * So far, the only boss shown to explicitly harness Orokin technology is Captain Vor.
 * The Corpus Fusion MOA and Oxium Osprey are the direct result of the Corpus utilizing advanced Orokin technology, as a rare (due to cost and rarity of Orokin materials) upgrade to normal MOA and Ospreys respectively.