Kortar was, in Klingon mythology, the first Klingon. With his mate, he destroyed the gods who had created them. (DS9 episode: "You Are Cordially Invited") As punishment, Kortar was condemned to ferry the souls of the dishonored on the Barge of the Dead to Gre'thor. (VOY episode: "Barge of the Dead")
The Klingon wedding ceremony recounts the tale of how Kortar and his mate joined together to kill the gods. (DS9 episode: "You Are Cordially Invited") That legend was also depicted on an antique bloodwine vessel Worf gave to Jean-Luc Picard in 2381. (TNG novel: Losing the Peace)
In the mid-23rd century, the great opera singer Qaov longed to play Kortar but made an enemy of the opera composter Tarrant. On the night when Tarrant's opera on Kortar the Mighty, Qunpu' choS (Twilight of the Gods) opened at the amphitheater at Krennla, Qaov committed Mauk-to'Vor. (ST reference: The Klingon Art of War)
- Kortar's mate goes unnamed on screen, though she is called "Lunob" in Losing the Peace and Baka in The Klingon Art of War.
According to the qeS'a' text, Kortar's mate was named Baka.
During the reign of the gods, Kortar once fought a ngeng roQ for a day. The amphibious creature was ten times the man's size.
When the Klingons became dissatisfied with the petty feuds and unreasonable demands for sacrifices of their gods, Kortar and Baka visited each village and made a call to arms. (ST reference: The Klingon Art of War: Ancient Principles of Ruthless Honor) Kortar was not only the first Klingon to draw breath but also more powerful than even the gods. They grew jealous of his might and scorned him. Kortar, unable to let this insult to his honor pass, resolved to slay them. (STO mission: "Afterlife") A year later, Kortar and Baka led a hundred warriors across the Balduq Plain to the qo'Sor, the giant tree that was the gods' home. The warriors climbed the tree, slew the gods and destroyed the great tree. Only the lump of the qo'Sor remained. (ST reference: The Klingon Art of War: Ancient Principles of Ruthless Honor)
B'Elanna Torres claimed to have encountered Kortar during a near death experience in 2376. Kortar called her a mongrel child and recalled the times when she almost ended up on the barge before. (VOY episode: "Barge of the Dead")
In 2409, a Klingon Defense Force away team travelled to the Barge of the Dead, where Kortar introduced himself as the ferryman after his crewman were defeated by the away team. The team inspired the dishonored souls aboard the ship to join in their battle against the Fek'Ihri Horde. Kortar warned them of an additional passenger he ferried to Gre'thor that night, Herron, Lord of the Dead. After the away team defeated the giant Fek'Ihri in combat, the barge arrived at the Gates of Gre'thor. Kortar did not join the fight against the Horde. (STO missions: "Afterlife", "The Gates of Gre'thor")