The D5-class battlecruiser was a type of starship introduced by the Klingon Empire in the 2120s that served for over a century and a half. Some of the first Klingon ships fitted with cloaking devices were D5 battlecruisers serving in the 23rd century. (ST reference: Klingon Bird of Prey Owners' Workshop Manual) They shared some design traits with the Raptor-class cruiser used in the same era by the Klingons.