The Shepard class was a Starfleet design in service in the 2250s, seen at the Battle of the Binary Stars and represented by the USS Kerala and the ill-fated USS Gagarin.
The class appears in the first season of Star Trek: Discovery. The USS Kerala is among the ships that answer the Shenzhou's call for help in Battle at the Binary Stars and fight T'Kuvma's assembled Klingon houses.
The USS Gagarin is seen in Si Vis Pacem, Para Bellum, under attack from Klingon ships that use the new cloaking screen to strike without warning. Discovery jumps in to defend it and destroys some of the attackers, but cannot stop the Gagarin being lost with all hands, a defeat that spurs the effort to break the Klingon cloak.
A third ship of the type, the USS Ride, is listed among the fleet in the same season. The class name is not spoken on screen and comes from production sources.