Klingon

• Appearance: Mammalian; dark skin, forehead crest, prominent spinal ridges, sharp incisors; on average taller, larger than humans
  • QuchHa' minority during 22nd and 23rd century look near-identical to humans
• Lifespan: over 150 years (DS9: "Blood Oath")
• Homeworld: Qo'noS
• Low tolerance for cold (DS9: "Change of Heart"; VOY: "Displaced")
• Magenta blood (The Undiscovered Country)
• Multiply redundant biological systems
  • Two livers, three lungs, eight-chambered heart, redundant neural functions (TNG: "Ethics")
• Children mature quickly (cf. Alexander)

History

• c.1900: First contact with Vulcans, leading to decades of war (ENT Novel: A Choice of Futures; TNG: "First Contact")
• 2151: First contact with Humans; Broken Bow, Earth incident (ENT: "Broken Bow")
• 2154: Qu'vat virus leads to creation of QuchHa' minority class in contrast to HemQuch majority (ENT: "Affliction")
• Early 2290s: Cure discovered for Qu'vat virus; QuchHa' cease to exist. Their former existence is largely denied or kept quiet with outsiders from this point forward. (TOS Novel: Forged in Fire; DS9: "Trials and Tribble-ations")