|First appearance:||"Breaking Benjamin"|
|Last appearance:||"Goodbye Yellow Brick Road"|
Sydney Caldwell was married to leading Federation xenoendocrinologist, Dr. Jefferson Caldwell. The two had a son, Benjamin Caldwell, in 2346. Sydney held the rank of commander at the time of Benjamin's birth.
Both her husband and son came to live with her aboard her assignments for limited periods of time. During dangerous missions or during wartime, both lived off-ship.
Aboard the Starship Cartwright
Sometime after 2346, Sydney Caldwell was promoted to captain and commanding officer of the USS Cartwright.
Sometime between gaining a promotion to captain and commanding officer of the Cartwright and 2360, the Cartwright crew discovered an ancient alien artifact and brought it aboard. When her son, Benjamin, went to have a look, it activated and altered his genetic structure. This alteration gave him an unnatural ability with deciphering and speaking alien languages. Investigations cleared her and her crew of any wrongdoings.
In 2360, Sydney Caldwell and her crew were lost when the Cartwright disappeared during the Federation-Tzenkethi War. She, as well as her crew, were presumed dead. (Star Trek: The Cantabrian Expeditions: "Breaking Benjamin")