The MCRN Cú Chulainn was a Morrigan-class patrol destroyer of the MCRN. At the close of the UN-MCR Cold War, the vessel was stationed near Ganymede on patrol, where it nearly spotted the Rocinante on its gravity assist to the moon. Later it was present at the Sol ring after the war.
Following the initial battle over Ganymede, the Cú Chulainn was patrolling the various moons orbiting Jupiter. During a gravity assisted slingshot maneuver to reach Ganymede undetected, the Rocinante narrowly avoided detection by the Cú Chulainn thanks to quick reactions by pilot Alex Kamal.
Later, following the UN-MCR War, the Cú Chulainn was among the ships defending the Sol gate during the Slow Zone blockade run. When the Belter ships running the blockade entered the Ring Space, the Cú Chulainn was among the ships that gave pursuit.
The ship was unnamed until the official breakdown of the class, in which the ship's name could be seen as well as the number "512" on the 3D model shown below.