The IKS Katai was a B'rel-class Klingon starship in the 23rd century.
In an alternate timeline, the Katai was commanded by Kruge when he traveled to the Genesis Planet. He would take David Marcus and Saavik aboard the ship as prisoners, and two months later he would try to trade the two hostages for information on the Genesis Device from James T. Kirk. Kirk and his crew would then capture the Katai and kill Kruge. Kirk would be killed aboard the USS Enterprise, but his crew (under the command of Thelin) would return to Earth aboard the Katai. The Katai would later be used by Thelin to deploy the Genesis Device on Praxis in an attempt to end the Genesis War.