Arno D'Vox was a commander in the Imperial Military. He was in command of Bannistar Station during the Galactic Civil War.
Nine months after the Battle of Yavin the battle-damaged Rebel One appeared at Bannistar Station, trying to hide between the civilian refueling queue. Despite using falsified registration codes, Rishyk, the head of security, ran an extra check and informed D'Vox that the ship actually was one of the Rebel Alliance's flagships. D'vox opened communications with the ship to warn them that they were to be boarded and had to move out of the refueling queue. He ordered a Nebulon-B escort frigate and three TIE/LN starfighters to approach the ship. When it appeared the ship was fleeing, D'Vox ordered his TIE fighter pilots to disable the engines. This had been part of the rebels' plans, their destruction would allow a few rebels to infiltrate and destroy Bannistar Station. Commander D'Vox saw through the rebels' ploy, however, and ordered his troops to hang back to see how far the rebels would be able to infiltrate.
When the rebels started planting their detonators, the stormtroopers moved in and confronted the rebels, following D'vox's orders that everyone but Skywalker and Senator Organa were expandable. Six rebels, among which Luke Skywalker and Leia Organa, were captured and transported to the command center of Bannistar Station. D'Vox realized how badly the Emperor wanted the two rebel leaders captured and saw this as his opportunity to get off Bannistar Station and get command over a Star Destroyer. He did not report their capture immediately however. First, he ordered Rishyk to find one rebel that eluded capture, Deena Shan.
After this order he informed the Emperor of the captured rebels and was ordered to sent them to the Emperor with the Star Destroyer Certainty when it had finished refueling. D'Vox then gloated about this to Leia Organa and also informed her that Rishyk had found Deena and the she probably was already dead. He was not aware, however, that shortly after this Deena Shan managed to escape Rishyk's capture and made her way to a walkway refueling a Star Destroyer. So when she managed to take out part of the station and the ship by throwing a detonator down the fuel line of one of the fuel tanks he was taken off guard and was not alert to Abel's escape attempt.
D'Vox is disarmed by Luke Skywalker.
While Bannistar Station exploded around them Abel managed to take out the stormtroopers guarding the control room and captured commander D'Vox. Rather dying than letting the rebels escape D'Vox grabbed one of the dead stormtroopers' rifles, but before he could fire Luke Skywalker used his lightsaber to disarm him, losing both his hands and part of his underarms in the process. While the rebels made their way off the station, D'Vox ordered the fleet to destroy the rebels' stolen shuttle. Nonetheless the rebels managed to escape with the help of Dagger Squadron and D'Vox swore to hunt down Luke and make him suffer.
D'Vox was an intelligent and confident middle-aged man. He was able to see through the fact that the Rebel Ones destruction merely served as a distraction to allow rebels to infiltrate Bannistar Station. He was sure that his troops would be able to overpower the rebels right before they would destroy the station. He also did not much care for unreasonable demands from Imperial Center and was not afraid to voice this opinion.
D'Vox was not satisfied with his position as commander of Bannistar Station, instead he wanted command over a Star Destroyer. By capturing and handing over Luke Skywalker and Leia Organa to the Emperor he hoped to accomplish this.
He also was not as strong follower of Imperial discipline. He himself would walk around, in front of his troops, with his uniform out of order and he allowed his head of security, Rishyk, to keep his hair uncut.
After Luke Skywalker cut off part of his arms, D'Vox sole purpose became to hunt down and make Luke Skywalker suffer.