(covers information from several alternate timelines)
The "Dauntless-class" was a type of starship used by Species 116 during the 2370s. Its name comes from the alleged Dauntless-class prototype, the "USS Dauntless", a ship of the line that was altered to appear Federation in design.
The Dauntless was equipped with a quantum slipstream drive, which allowed it to go faster than the standard Starfleet warp scale at the time. It could travel 60,000 light years in three months and was capable of traveling over fifteen light years in only a short time, which otherwise took the USS Voyager two days to cover at high warp.
Although created by alien technology, at least one ship of this class was made to resemble Federation starships on the interior and exterior by the means of particle synthesis. The darker alien interior was modified to a more familiar Federation color palate, and LCARS interfaces. The exterior of the vessel was also modified with familiar Federation markings and ship's registry. (VOY: "Hope and Fear")
In a possible future, the Federation appeared to have adopted this design by the 26th century, with at least one Dauntless-class starship participating in the pivotal Battle of Procyon V. (ENT: "Azati Prime")
Ships of this class
Though not originally a Starfleet design, ships matching the configuration of the Dauntless appear in the 25th-century timeline of Star Trek Online as the Dauntless-class "Experimental Science Vessel", featuring a special device that mimics the effects of particle synthesis to distract enemies and confuse their targeting.