Kahless (also known as Kahless The Unforgettable) is a Klingon mentioned in many Klingon histories. A clone named Kahless was created from the blood of a dagger.
Supposedly, Kahless was a great warrior who freed his people from tyrannical rule. He also created the first Bat'leth from a lock of his hair that he dipped in molten magma. There was a great war, and Kahless' followers won. However, in the process of ousting Molor (the evil dictator), Molor supposedly stabbed Kahless with a dagger. It was from the dried blood from this dagger that the clone was created.
In the book, Kahless, written by Michael Jan Friedman, it appears that Kahless was not the one who was stabbed; the clone is not that of Kahless, but of Kahless' friend, Morath. In the book, Morath is the one who led the rebellion, Morath made the first Bat'leth, and Morath was stabbed and lost his life protecting Kahless. However, this may not be accepted in the general Trek universe.The History of Kahless
Other Theories