The Klingon warbird was a class of warship used by the Klingon Empire in the mid-22nd century and in the mid-23rd century of the alternate reality.
In 2151, the Vulcan diplomat Tos claimed that the Klingons would have sent a squadron of warbirds to attack Earth, had he not negotiated for the transport of Klaang's corpse to Qo'noS on the Enterprise (NX-01)
In an alternate reality, five simulated Klingon warbirds were incorporated into the Kobayashi Maru scenario. These warbirds were capable of cloaking, had shields, and were armed with photon torpedoes. During James T. Kirk's third attempt at the scenario in 2258, two of these vessels entered the neutral zone before locking weapons on the USS Trainer captained by Kirk. Moments later, the three other warbirds decloaked while targeting the Starfleet craft, and then began firing torpedoes as they simultaneously maintained shields. After the simulation was affected by a subroutine that Kirk had secretly inserted, the warbirds' shields were suddenly eliminated and the Klingon vessels were all vulnerable to a single photon torpedo strike each.
Shortly before, Cadet Uhura heard a transmission that 47 Klingon warbirds were destroyed by one Romulan ship (which turned out to be the Narada) when it attacked the Klingon prison planet.