USS Nautilus
From Star Trek: Theurgy Wiki
The USS Nautilus was an Excelsior class Federation starship operated by Starfleet in the mid 24th century.
Leon Marquez spent his childhood aboard the Nautilus as a dependent of his parents, a soccer player-turned Security enlistee and a flight control officer named Alan and Rose Marquez. The starship saw action against the Cardassians during the Federation-Cardassian conflict of the 2350's and 2360's. During this time, the Nautilus was commanded by Captain Xan of Andoria. When Leon Marquez was a teenager, Captain Xan became his mentor and made him acting ensign until young Leon saved the ship by defying orders. Xan 'punished' the young man by sending him to Starfleet Academy.
In 2360 Liliana Walton completed Starfleet Boot Camp and joined the CONN department of the Nautilus with the rank of crewman. In 2364, she was promoted to petty officer third class and transferred to the USS Hiroshima.
(So far it is unknown if the Nautilus is still serving Starfleet in 2381. The DS9 episode "Tears of the Prophets" would indicate that the USS Nautilus was a Miranda class, but it is possible that name may have been given to an Excelsior in the Star Trek: Theurgy universe.)
