Starfleet helm officer serving aboard the U.S.S. Enterprise NCC-1701-C. In 2344, Castillo and the rest of his crew were transported ahead in time 22 years after passing through a temporal rift caused by a torpedo explosion during a battle with Romulans at Narendra III. This altered the timeline briefly and the U.S.S. Enterprise NCC-1701-D came into contact with its predecessor. In this time, Castillo befriended Natasha Yar from the latter day Enterprise. However, his ship and crew agreed to return to their own timeline where they subsequently met their fate. Accompanying Castillo was Yar, who was told by Guinan in the current timeline that she did not belong there.