Klingon

"A Klingon's honor means more to him than his life!" – Kurn

The Klingons (Klingonese: tlhIngan) were a humanoid warrior species that originated from the planet Qo'noS (pronounced Kronos), an M-class planet. One of the major powers of the galaxy, the Klingons were a proud, tradition-bound people who valued honor and combat. The aggressive Klingon culture had made them an interstellar military power to be respected and feared. Klingons believed that they had the instinctive ability to look an opponent in the eye and see any intent to kill.

History and Politics
The Klingon Empire was founded some time in the 9th century by Kahless the Unforgettable[], who performed many heroic feats including the unification of the Klingon people when he killed the tyrant Molor[]. Kahless came to be revered in Klingon society to the point of near-deification, and many aspects of Klingon culture came to revolve around emulation of Kahless's life. (TNG: "Rightful Heir")

The warrior ethos had been an important aspect of Klingon society since the time of Kahless, but the warrior aspects became much more dominant beginning in the early 22nd century. Previously, Klingon society was regarded as socially balanced, but over time the warrior caste gained greater prominence, to the point where the Klingons widely came to be regarded as a "warrior race." (ENT: "Broken Bow", "Judgment")

Because of their aggressive outlook, the Klingons generally had poor relations with other races after they began to move out into space. Because the worlds of the Klingon Empire were resource-poor, the Klingons developed an intense belief in the need for expansion and conquest in order to survive. The Klingons' relationship with Humans and the Federation was rocky at best. Following the disastrous First Contact between Klingons and Humans, tense rivalries and unavoidable conflicts often developed between the two races. (TNG: "First Contact"),