Frigate classed ships fall below cruisers in the mass classification scales used on interplanetary ships. The most famous class of frigates, the Dreadnought Classed Interstellar fast assault frigate, or DCI frigate, earned that position by being the first interstellar ship to be almost entirely autonomously operated. Only four crew were required for the total upkeep of the ship outside of battle. After the Alien War the DCI frigates were retired, and the class was never constructed again, but the technologies pioneered by the ships came to see common use in nearly every Hawking drive outfitted ship, as well as inspiring the design of future battlehulk classes.
The relatively small size of frigate classed ships (between 300,000 and 500,000 metric tons) means that they are more economical to build, and as such there are simply a much greater variety of them. Some of the more common are the Mission Keeper Kerry (MKK) class colony ship, the Iiligunous High class merchanteer, and the Directed Heavenly Uniform Clerical Keep (DHUCK) class mission ship. There are a dozen variations based on each of those original designs, and a hundred designs that were either extremely niche or generally flawed.
Some of the more entertaining failures in ship design have happened in the frigate mass class. The original followup to the DCI frigate, the Terran Pride, was intended to define ship design for the next hundred years. When designed, however, somebody rounded an internal dimension metric when they clearly shouldn’t have, and the final product had crew quarters that were literally outside the hull. A budget version of the popular MKK class frigate was created for aspiring colonists that wanted to break into the private sector without a sponsoring corporation. Development was undertaken below the cloud line of Venus, and corners were cut wherever possible. When they were approaching the end of development, someone realized that they’d essentially built a submarine instead of a spaceship. A prototype was sent on an autonomous mission to orbit the planet, and the pressurized outer hull popped. The ship was only suitable for colonists interested in cruising around the ancient Venusian skyways below the cover of sulfuric clouds. DHUCK class ships were originally built by the Directed Clerical Corporation, and the name originally given to them by the marketing material was Uniform Heavenly Keeps. But the Directed Clerical Uniform Heavenly Keep class was too much of a mouthful, and DCUHK is an incredibly unwieldy acronym. Then a disgruntled marketing intern realized that the acronym could be rearranged to nearly spell “duck”, and was able to rearrange the title on all marketing material just before a delivery of more than 200 ships. Directed Clerical Corp marketing material is far more distributed now.