Kahless "The Unforgettable" is a fictional character in the Star Trek media franchise. He was portrayed in Star Trek: The Original Series by Robert Herron and in Star Trek: The Next Generation by Kevin Conway; and is the titular character in the Star Trek novel Kahless by Michael Jan Freeman. Kahless is an important religious and historical figure to the Klingon race and has been studied in explorations of the philosophy within the setting of Star Trek.Kahless was also the subject of a Klingon language opera in the Netherlands. Source: Wikipedia (en)