The Protostar class was a small experimental Starfleet design of the 2380s powered by a contained protostar, able to make enormous jumps at speeds far beyond conventional warp.
The class is represented by the USS Protostar, the hero ship of Star Trek: Prodigy. Built to return to the Delta Quadrant under Captain Chakotay, it carries two warp cores for ordinary flight and a third engine, the proto-drive, which taps a newborn star held in containment. When the drive is engaged a third nacelle unfolds from the hull.
The ship has a small crew, a vehicle replicator that can build shuttles, and a holographic training adviser modelled on Kathryn Janeway. In the first season a group of young fugitives find it buried on Tars Lamora and learn to fly it.
The original is destroyed to stop a weapon hidden aboard it. A second ship of the class is later launched and given to the young crew as the USS Prodigy.