Captain Sarkli was an Imperial officer who appeared in Return of the Jedi, a nephew of Firmus Piett. He was present on the Death Star when Darth Vader's shuttle arrived. In the movie, it is not known whether or not he survived the Battle of Endor.
In Star Wars Rogue Squadron 3: Rebel Strike, it is proven that Sarkli became a part of Rogue Squadron after the death of Biggs Darklighter. Eventually he defected to the Empire on the moon of Yavin IV, feeling like he didn't get appreciated enough in the Rebellion, and became a Storm Commando Captain. He was present on the Death Star when Darth Vader's shuttle arrived, and reassigned to the Endor shield bunker during the Battle of Endor, in which he was killed by Han Solo seconds before the bunker blew up.