Regent Worf's bird-of-prey was a Klingon starship, a K'vort-class bird-of-prey in Klingon-Cardassian Alliance service in the 2370s decade. The vessel was under the command of a version of Worf, Regent of the KCA. (ST video game: Star Trek Timelines mission: "Prologue")
History
When the temporal anomaly crisis engulfed the galaxy in 2379, a version of Worf from the mirror universe arrived with a KCA fleet in the 40 Eridani system and began an occupation of planet Vulcan because it was home to Emperor Spock in Worf's reality. The captain of a Federation Constellation-class starship convined Worf he and his forces had arrived in a different universe but the regent still sought revenge against the despised despot Spock. After the Starfleet ship bested Worf's bird-of-prey in battle and Federation troops liberated Vulcan, Worf agreed to a peaceful resolution, and the KCA faction relocated. (ST video game: Star Trek Timelines "Prologue" mission: "A Show of Force")