The Shepherd ship was a type of starship used by the Shepherd species in the mid-23rd century to protect ancient comets that they venerated as Arbiters of Life. These vessels were substantially larger and more technologically advanced than a Federation Constitution-class starship, endowed with superior speed and firepower. They were equipped with several forward torpedo launchers and a tractor beam.
When the USS Enterprise attempted to prevent the comet C/2260-Quentin from impacting Persephone III in 2259, a Shepherd ship identifying itself as the escort of the Arbiter M'hanit interceded and threatened to destroy them if they interfered with the comet any further. As they were tactically outmatched by the Shepherd ship, the Enterprise crew implemented a plan to make it seem as though M'hanit diverted to a new course on its own. (SNW: "Children of the Comet")