(covers information from several alternate timelines)
The Vidiian starship was a massive starship utilized by the Vidiians in 2371 and 2372. This class of vessel operated with a crew of well over three hundred, and was armed with hyper-thermic charges and grapplers, which was used to access captured ships.
In 2371 of an alternate timeline, Kes of the original version of 2376 contacted one of these vessels which was used to herd USS Voyager towards a subspace vacuole where it ambushed the ship. Kes betrayed Voyager in exchange for transport back to Ocampa. Voyager was damaged by the vessel, but the Vidiian vessel was defeated in the battle they fought. (VOY: "Fury")
In 2372, the USS Voyager was attacked by such a ship when it was trapped in a plasma drift. At the time, Voyager was experiencing the effects of a subspace divergence field, which effectively created two ships, one of which was unseen to the Vidiians.
The Vidiians attacked one of the Voyagers and destroyed its weapons array, before maneuvering the ship into grappling range and boring an access route through Voyager's hull on deck five, before Voyager was boarded by over 347 Vidiians.
Later that year, when Harry Kim suggested to Tuvok that they should contact the Vidiians in order to help find a cure for a virus contracted by Janeway and Chakotay, Tuvok reminded Kim that Voyager was recently responsible "for the destruction of a Vidiian ship, an act which killed over three hundred of their people. That alone makes it unwise for us to contact them." (VOY: "Resolutions")