The ship hijacked by Khan to chase the Genesis device.
The USS Reliant was a Miranda-class starship with a distinctive weapons pod mounted above its saucer. In Star Trek II: The Wrath of Khan, it was commanded by Captain Clark Terrell, with Commander Pavel Chekov as first officer, and was assigned to find a lifeless planet on which to test the Genesis device.
The crew thought they were surveying Ceti Alpha VI, but the planet had exploded years before, and they were in fact on Ceti Alpha V. There they found Khan, whom Kirk had exiled, and his surviving followers. Khan used mind-controlling eels on Chekov and Terrell and seized the Reliant.
Khan used the ship to raid the Regula One station and then surprised the Enterprise, causing heavy damage. In the final battle in the Mutara Nebula, Kirk outmanoeuvred him and disabled the Reliant. The dying Khan activated the Genesis device, and the Reliant was destroyed in the blast that formed the Genesis planet.