A Blood debt is a Klingon custom in which, after being dishonored, a Klingon warrior seeks to regain his honor by killing the person responsible for their dishonor.

In 2254 Christopher Pike received a blood debt from Kaaj, son of Torg following the Klingon's humiliating defeat at the Pharos siteworld. A short time later Kaaj attempt to call the debt by setting a trap for Pike, but once again he was defeated and forced into retreat. (EV comics: "The Fires of Pharos", "The Flat, Gold Forever")