Kahil Grigesh is the name of a vampire from Vaeternus who became a victim of the kris sword Datusha. The sword manipulates its holder into believing that they are slaying evil beings for a greater good, and as such Kahil slaughtered many of his vampire kind. He managed to break the sword's hold on him, and to make amends for the deaths he'd caused, he took Datusha into the plains of the Netherrealm and committed suicide, trapping the sword there. However, later on, it was found by the demon Ashrah.
TriviaOn Ed Boon's Twitter account, he posted a screenshot of a previously unrevealed character from Mortal Kombat: Deadly Alliance. This one is a male vampire character with wild blue hair, who was never 100% completed. However, it is possible it depicts Kahil Grigesh. According to Boon:
"Cutting Room Floor - Nitara from Deadly Alliance originally had a male counterpart but we decided not to finish him"