A Klingon claiming to be an adviser to the House of Mogh who was in fact a future Alexander Rozhenko traveled back in time.
K'mtar introduces himself as a gin'tak, an adviser to the House of Mogh sent by Kurn. He protects Worf from an attack at the Kot'baval festival on Maranga IV and then sets about turning Alexander into a warrior.
In Firstborn, K'mtar's harsh methods fail, and he threatens to take custody of Alexander. Worf discovers that K'mtar is actually an adult Alexander from the future, who had come back in time hoping to change his younger self so that he could save his father from being murdered. He was played by James Sloyan.