Weapon ship

A weapon ship was a starship classification denoting mobile superweapons, built with the sole purpose of dealing a crippling blow to an enemy. The most powerful weapon ships were capable of destroying a planet. 

History and specifications
The s constructed a planet killer to combat the Borg Collective. Let loose, these Doomsday machines attacked innocent worlds. 

In the 22nd century, the Xindi Council targeted Earth with the Xindi superweapon. 

Around the 2170s decade, the Krenim military scientist Annorax developed the Krenim temporal weapon ship, a vessel capable of selectively erasing a single molecule or an entire civilization from the timeline. 

In 2376 and 2377, the Romulan suicide ship was capable of opening a destructive rift to subspace. It's Klingon counterpart was the subspace weapon ship. 

In the 2480s decade, the Raqilan launched their own temporal weapon ship, the Poklori gil dara. The ship was capable of destroying a planet and was sent to the past to act as a deterrent to prevent the war with the Golvonek. 

Planet killer

 * s: Doomsday machine
 * Xindi Council: Xindi superweapon

Temporal weapon ship

 * Krenim Imperium: Krenim temporal weapon ship
 * Raqilan: Poklori gil dara-type