Alvis Preston was a captain in the Imperial Navy, who served under former admiral-turned-warlord Celie Namgadi.
Preston was born on Coruscant, joining the Imperial Navy at a young age. He showed an exceptional degree of tactical sense and cunning, leading to him being rapidly promoted. At some point about the time of the death of the Emperor, he was given command of the Super Star Destroyer Atom Smasher, which served as Admiral Namgadi's flagship.
Alvis participated in numerous battles both for the Imperial Navy and later Warlord Namgadi. One of these saw him face off against and defeat a force from the Hapes Consortium. After the battle, he wrote an essay on the subject, Hapans are Stupid (Or how to shamelessly exploit the conceptual, design and tactical flaws of the Hapan Battle Dragon) which is considered to be definitive.
Despite his tactical skill, Alvis found himself being impaired by Namgadi's less than stellar leadership. In the most extreme cases, he found that his own ideas for offensive operations were being overruled and replaced by incompetent scrawling of Namgadi's own devising. He was especially vocal on the subject of the Nostril of Palpatine, feeling that the ship needed better protection against a potential Rebel attack.
Ironically, when the Nostril was actually attacked, Alvis and the fleet were occupied on another pointless raid ordered by Celie. As a result, they were unable to respond to her calls for reinforcements and both the Superweapon and its creator were lost. Alvis' whereabouts since then are unknown.