Duchess Senna was a Hammerhead corvette that served in the Alliance to Restore the Republic's fleet. The Duchess Senna was one of three Hammerhead corvettes that were sent by Senator Bail Organa to reinforce Commander Jun Sato's unit. The ship was stolen by the Spectres during a raid on the planet of Lothal.
Behind the scenes
The source book Star Wars: The Rebel Files – Deluxe Edition identifies the three hammerhead corvettes that appeared in A Princess on Lothal, the mid-season premier of the second season of Star Wars Rebels, as Lightmaker, Duchess Senna, and Amity's Arrow.  While the episode guide on StarWars.com identifies them as P1, P2 and P3. It has not been clarified which names mentioned in the Rebel Files corresponds to the ships identifed by the episode guide.