The IKS Katai was a B'rel-class starship in the 23rd century.
In an alternate timeline in which Spock was killed in 2237, the Katai was commanded by Kruge when he traveled to the Genesis Planet in March 2285. He took 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 the captured the Katai and kill Kruge. Kirk was killed aboard the USS Enterprise, but his crew (under the command of Thelin) returned to Earth aboard the Katai.
The Katai was used by Thelin to deploy the Genesis Device on Praxis in an attempt to end the Genesis War. (TOS - Myriad Universes novel: The Chimes at Midnight)
- The vessel may have been named for the Katai masters.