Nural

Sub-Commander Nural was the first officer of the Romulan Warhawk Shakalak. The ship was the only one of three warhawks to survive ambushing a Vulcan frigate. It escaped to Federation space, at which point it was repaired. The Shakalak was short a tactical officer after fighting the Vulcans, so Lieutenant Commander Tovar took the opportunity to escape his troubles on the USS Anomaly by volunteering to serve in the position. Once Tovar was aboard, Nural revealed to him that she was actually his adopted sister Audrey Bain, who had been sent by Section 31 because events on the Shakalak and with the Vulcans were not what they seemed. She told him that they would be saving Earth but they wouldn't be coming back. (Strategic Retreat [BG])

As far as the Romulans know, Nural was killed by the Vulcans while trying to stop their plan to obtain the Kolch'ak Device. (Scratching The Surface [BG])