One of the ship classes of warships used by the Sith Empire

Old Sith Empire Organization Galaxy-Wide Organizations

during the Great Hyperspace War

Great Hyperspace War Event Old Republic Era

and later by another Sith Empire

Revan's Sith Empire Organization Galaxy-Wide Organizations

during the Jedi Civil War

Jedi Civil War Event Jedi Civil War

.
At the beginning Great Hyperspace War Sith Empire's vast invasion force had significant numbers of such warships.
Sith warships were among the most powerful and fearsome warships of their time, despite sporting no shields. One vessel was said to succumb only to the firepower of six main Republic warships, thanks to its heavy armor, and even then was able to cripple or destroy at least one of the opposing ships.