- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
Planet: Q'onoS (Kronos, the Klingon homeworld).
The well-statured warrior race has a genetic predisposition to hostility and a well-known streak of fatalism. Lieutenant Worf says that Klingons do not like to be "probed" by empathic species. The culture's warrior ethic runs so deep that rivals in the civil war can meet and drink as equal fighters for periods of time before or after battles, thanks to the Capitol City's neutrality. During these get-togethers, a great deal of growling, wrestling, snarling and generally loud revelry takes place, Klingons seeming to derive tremendous satisfaction from drinking with their enemies on the night before a battle.
A beard is a symbol of courage; a hammer is a symbol of power. A true warrior fights to the death and would rather be killed than taken hostage — an act which brings dishonor on himself and his family for three generations. Their most important historic symbol of leadership, Kahless, said Klingons should fight not just to spill blood but to enrich the spirit. Their scientists are not highly regarded in the culture. Shattering the cranial exoskeleton at the tricipital lobe brings instant death.
In the traditional sense, the Klingon people hold honor above life — although as with any culture, high-level politics and personal gain get in the way. In Klingon culture, lower-ranked officers consider it a duty to kill off a superior who is perceived as weak. Klingons notoriously neither surrender nor bluff, although Chief Engineer La Forge is skeptical of that based on Lieutenant Worf's seemingly impenetrable "poker face" during their poker games on board the U.S.S. Enterprise NCC-1701-D.
The Klingon Klag on board the Pagh admits he does not speak to his father, who is slowly dying on the homeworld without honor after escaping from victorious Romulans who would not allow him to die as a Klingon should die — in battle.
Klingon language had no word for the concept of "peacemaker" until Ramatisian mediator Riva negotiated the early United Federation of Planets-Klingon treaties just decades ago.
Warriors and their families are responsible for each other's actions. A challenge to clear a family's name, such as Lieutenant Worf's, ends in death if unsuccessful. They believe that death is an experience best shared and view it as a joyful time for one who falls in the line of duty and earns a place among the honored dead, celebrating the release of a dead spirit rather than grieving over what they consider to be the empty shell of the body. One of the most honorable deaths is a kamikaze-like suicide that takes an enemy's life with it. Viewed through their Spartan perspective, illness (especially terminal) is not honorable. One is not supposed to faint, at least as an adult, a bias that leads to a lack of both research and sympathy for such patients. Usually cases of paralysis such as Lieutenant Worf's are left to die — or to perform the ritual suicide Hegh'bat. Of course, half-human Federation emissary, K'Ehleyr thought it was just more "Klingon nonsense" and "dumb ideas about honor."
Lieutenant Worf says Earth and humanoid females like the Edo are too fragile for what his race considers love, although that would likely apply to a Klingon of either gender with a human mate. A roaring yell akin to the death wail is the Klingon female's mating call, Worf says, followed by their hurling of heavy objects and clawing. The male responds by reading love poetry — and ducking a lot. A form of dominance/submission is seen when he is given a Klingon female thanks to Commander Riker's temporary Q powers; she is donned in leather accessories and some armor, she seems jealous of Yar, takes a strong slap from Worf and comes back on her knees — defiantly growling. The actual act of love can be intermingled with pain and include the Klingons' highly developed sense of smell. Once aroused, the combat as well as passion instinct appears hard to quell; it takes a sharp command to snap Lieutenant Worf and later K'Ehleyr out of their bloodrush.
Klingons usually mate for life, celebrated with a solemn Oath of Union, most often in private, rather than in a public ceremony like marriage; judging by Lieutenant Worf's initial issuance of the Oath of Union to K'Ehleyr, the Oath doesn't appear include much talking, and no dancing or crying as in human weddings. If Lieutenant Worf is any example, male chauvinism is much more pronounced in mainstream Klingon society than among humans.
Lieutenant Worf echoes the modern Klingon attitude toward Romulans when he says the enemy "considers humans and Klingons a waste of skin". Romulans and Klingons having been "blood enemies" for 75 years (or since about 2292), after an extremely brief alliance.
Klingons apparently hold the Ferengi with almost as much disdain as they do Romulans, thinking them loud of talk, yet weak in action. Klingon officers do not let their children live with them as a general rule, although "the son of a Klingon is a man the day he can first hold a blade". Lieutenant Worf allows his son, Alexander, to stay with him on the Galaxy-class Enterprise when other options run out, though he says it is inappropriate for a Klingon to receive family while on duty and Klag says a Klingon "is his work, not his family."
Klingons are remarkably skilled hunters, relying on their keen olfactory senses to pick up and stalk their prey. They eat their meat raw, seasoned more strongly than humans prefer, and find the human tradition of "burning their meat" to be somewhat repulsive. If Lieutenant Worf is any clue, they regard swimming with as much disdain as they do bathing. At least once, Klingons use the United Federation of Planets' Earth-derived metric system. Lieutenant Worf contends that love poetry and the great novel both reached their height with the Klingons.
T'kar and Yeto were two more Klingons who had no respect for the Klingon Empire's current state of affairs. Kang fretted that the warrior ethic was lost among modern Klingons who would open restaurants and such. Science Officer Dax said that getting Kang angry at Curzon was the only way to begin to create a bond between the two — a Klingon truism, Kang agreed.
The custom of naming godparents or other relatives is practiced among Klingons as well as humans. The Jem'Hadar, Third Talak'talan, expressed regret that his first experience with an Alpha Quadrant being was not with a Klingon warrior, but with Federation humans and a Ferengi instead, both of whom he considered weak.
Despite the disillusionment and disrespect of some Klingons, Klingon honor still counts among the peoples. D'Ghor was not allowed to claim the House of Kozak based on financial debts alone, and he was stopped and shamed while attacking the unarmed Quark before the High Council. Grilka and Gowron alike sneered at financial matters and normally considered them beneath a warrior's time and attention, charging D'Ghor with using "money to bring down a great house". Even so, Quark was able to resurrect a plenitude of complex financial records.
Challenges to personal honor are settled usually by personal combat, but Quark used numbers. Klingon females — banned from holding Council seats — are not even allowed to head their heirless dead husband's house, except in special cases. The Klingons must have some class system, as personal servants are used, usually among what appear to be the poor. Due to their rough nature, especially when drunk, Quark charged Klingons double for holosuite use, and then raised it to triple normal cost. The Klingons' profound hatred of Romulans continues.
Although they believe in an afterlife, Klingons perform no burial ritual and dispose of the corpse by the most efficient means possible — although some archeological digs on Qo'noS revealed different customs at one time.