Captain Dexar was a male Starfleet officer active in the 24th century. By 2381, Dexar had ascended to the position of commanding officer of the USS Aventine. However, during the Borg Invasion of 2381, the Aventine engaged a Borg cube at Acamar and Dexar and first officer Tovak were killed. Ezri Dax assumed command and successfully led the Aventine through the Battle of Acamar and was eventually assigned as the replacement commanding officer. (ST - Destiny novel: Mere Mortals)