Abaddon was the owner of a Delta Quadrant junkyard and space station. In 2376, the crew stopped there to trade. He sold Alice, a supposedly "haunted" ship, to Tom Paris.

When strange things began happening to Paris, the USS Voyager contacted Abaddon to ask if he could help. He informed them that the ship was sold to him by a Haakonian trader, who claimed it was haunted. However, when he attempted to give further information, Alice appeared to Abaddon, looking like a member of his own species, and ordered Abaddon to remain silent. Literally almost frightened to death, he suffered a cerebral hemorrhage. The Doctor was able to help him and gave him a cortical suppressant to prevent any further attacks. Abaddon revealed that he was once linked with Alice, who used a neurogenic interface to torment him until he found a pilot to guide her to an unknown point in space. (VOY: "Alice")

Abaddon was played by Star Trek regular John Fleck.
Abbadon was described in the script as "an elderly exotic alien... weathered as his old station."
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