Gaul was a male Vaadwaur soldier. In the Earth year 1484, his battalion and their families, approximately six hundred Vaadwaur, went into stasis on their homeworld after an attack by their enemies, including the Turei.
He was awakened by an away team from USS Voyager. He was in command of the rest of the Vaadwaur, who were also awoken from stasis. He told Captain Kathryn Janeway that if she helped him and his people escape from their planet, he would give them directions to subspace corridors that could cut years off Voyager's journey.
In reality, his plan was to seize Voyager and use it to attack his enemies and restore the Vaadwaur empire. Janeway and the Voyager crew were able to foil the plot when one of the Vaadwaur, Gedrin, along with Tuvok returned to the surface of the planet to help the Turei find the Vaadwaur ships using a Vaadwaur communication satellite. The Turei attacked the Vaadwaur fleet, destroying many ships, allowing Voyager to escape. (VOY: "Dragon's Teeth")
Gaul was played by Robert Knepper.
Gaul is the main antagonist of the Delta Rising expansion to Star Trek Online; in the roughly three decades since their encounter with Voyager, the Vaadwaur have united under his leadership to become a powerful military force intent on conquering the Delta Quadrant. Near the end of the Delta Rising story, several members of the former Voyager crew (Admiral Tuvok, Captain Harry Kim, Seven of Nine, The Doctor, and Neelix) lead a coalition of several Delta Quadrant races, as well as Vaadwaur revolutionaries fighting against the bluegill-infested Vaadwaur leadership, to defeat Gaul on the destroyed Vaadwaur homeworld.