Inspired by the ships of the same name within the game Black Flag, I wondered: what were the strongest ships of the various Star Trek series? Excepting the 'hero ships', like the various Enterprises, the Defiant, or Voyager. The ones that were nigh impossible to defeat. These are my opinions. Any I may have forgotten?
TOS: The Fesarius
From "The Corbomite Maneuver", it was a sphere a mile in diameter and scanned Kirk's Enterprise in a few seconds and managed to override and shut down some of its systems. It took some quick thinking and bluffing by Kirk - and, admittedly, no real malevolent intentions by Fesarius' pilot - to defuse the situation.
TNG: Borg Type 03
From the "Descent" two parter, operated by the rogue Borg under the leadership of Lore. Heavily armed and massively armored, it completely outmatched the Enterprise-D and forced it to retreat instead of being able to stand toe to toe with it. It took metaphasic shielding to hide in a star's corona from it, and an induced solar flare to destroy it.
DS9: Jem'Hadar Battleship
Introduced midway through the Dominion War, this battleship was said to be twice the size of a Galaxy-class and three times as powerful. It completely outclassed a Defiant-class ship, though it was admittedly piloted by a bunch of Starfleet cadets, albeit at the top of their class.
VOY: Krenim Weapon Ship
Technically not legendary - because it never existed in the first place - in an overwritten timeline, this Krenim temporal weapon was the scourge of a section of the Delta Quadrant for two centuries. It could move ships and entire worlds out of the space-time continuum, effectively erasing them from history. Outside of the normal flow of time itself, its crew was immortal and the ship was immune to conventional weapons. Even without its temporal core active, its conventional defenses were formidable as well. Only through internal dissent was the ship defeated, erased from history itself, and the Year of Hell Voyager went through never happened in the first place.
ENT: Xindi-Aquatic Cruiser
Some might say the spherical Xindi weapon that could destroy entire worlds might fit better, but it was obvious that it needed a fleet to defend it and that it was a one trick pony - it could destroy planets, but nothing else. Ships would likely be too fast for it to target. So the Xindi-Aquatic Cruiser. At least 1800 meters long and equipped with the most advanced technology of the five Xindi species. It had a hangar that could carry an entire starship. It was destroyed by spatial anomalies generated by a nearby Sphere as it was certain to carry its side to victory otherwise.
Comments
...V'Ger...
VOY: ATR-4107 codenamed "Dreadnought" from the eponymous episode.
...Oh, baby, you know, I've really got to leave you / Oh, I can hear it callin 'me / I said don't you hear it callin' me the way it used to do?...
- Anne Bredon
As for Dreadnought, it was indeed nigh impossible to defeat from the outside. Still though, I think the Krenim Weapon Ship has it beat - it's practically invulnerable as long as the crew keep the temporal core active and it can erase whatever it aims at from history, unless it figures out the temporal shielding. Which Dreadnought might do, but would it be able to in time, so to speak, before the Krenim's first shot erases it? The most that could happen is a draw between the two.
TOS: The Space Amoeba. I know, its not a ship but its the most formidable threat that I can remember. This thing is not only huge (I mean HUGE) but its negative energy field completely drains anything that gets close to it. Very similar to the doomsday machine, but its weakness isn't quite as apparent.
Honorable mention: The Doomsday Machine. Seems invincible, but is far from it once you figure it out.
TNG: The Borg Cube. During the first encounter, Picard had to BEG Q to safe them. The second encounter saw the loss of 39 Starfleet Vessels and left the Sol systems' defenses in pieces.
Honorable mention: The Husnock Warship. Technically just an illusion that may or may not be based on a real ship. It completely dominated the Enterprise.
DS9: The Dominion Battleship. A behemoth bristling with weaponry.
Honorable mention: Breen Warship. It took out the Defiant in one shot and only the Klingons were remotely resilient against the Breen energy dampening weapon (at least at first).
VOY: Species 8472 Bioship. Resists even Borg weapons and assimilation and can effortlessly destroy a cube. If multiple ships focus fire, they can even blow up a planet!
Honorable mention: The Krenim Timeship and the Tactical Borg Cube.
Sadly I cannot comment on ENT since I haven't seen most of the episodes. The encounter with the (alleged) Elachi ship was tough though, since the Enterprises' primitive weapons weren't particularly useful at first. Thats the only such encounter I can remember.
"Let them eat static!"
I'd say it was a living ship. It sustained a crew and was seemingly intended to do so.
Tamarian warship- effectively traded fire with the Enterprise, and was clearly winning until Picard used diplomacy and it was super effective.
APU Battleship- again, took on Voyager in a straight up fight and forced them to withdraw. I don't even remember Voyager scoring any lasting damage against it-- I think the only damage it ever suffered the whole episode was from rival APU vessels.
Octanti warship- "twenty-two phaser cannons on its aft section alone."
It took a fair beating in changing face of evil before it was destroyed.
-Lord Commander Solar Macharius
Ent: U.S.S. Enterprise-J Because why fly a starship when you can fly a space station