The legendary warrior who unified the Klingon people and founded the Klingon Empire.
Kahless the Unforgettable is the legendary warrior who united the Klingon people and founded their empire many centuries before the Federation era. Klingon tradition credits him with defeating the tyrant Molor and with forging the first bat'leth, the Sword of Kahless, from a lock of his own hair, and his teachings form the core of Klingon ideas about honor.
In the original series episode The Savage Curtain, the Excalbians create a likeness of Kahless and set him against Kirk and Spock alongside other figures from history. In The Next Generation episode Rightful Heir, clerics on Boreth produce a clone of Kahless and present him as the promised return of the emperor. Once the deception is exposed, Worf proposes a compromise that Gowron accepts: the clone is installed as a ceremonial emperor and spiritual figurehead while real power stays with the Chancellor and the High Council.
The legend also drives the Deep Space Nine episode The Sword of Kahless, in which Kor, Worf and Jadzia Dax search for his lost blade.