Nemesis

The Nemesis (ネメシス, Nemeshisu) is a legendary, fearsome, mighty, heavily-armed and most powerful Decepticon warship ever built, originally under the command of Megatron, the Decepticon leader, in their search for the AllSpark. According to both Zeta and Optimus Primes, its markings indicate that it is also the central command flagship of the Decepticon fleet.

It had a Grand Mal class force field, a cybertroid alloy star drive, Moleculon missiles, and a sophisticated sensor array. Unknown to the Autobots, it carried the protoforms stolen from Master Yoketron's dojo.

"When it comes to battling Autobots in Space; always come prepared the artillery big, and plentiful."
 * —Megatron on Nemesis' armaments.

History
The Nemesis was the ship used by the Decepticons to pursue the Autobots as Ark departed Cybertron, and engaged it in a fierce ship-to-ship battle in front of the space bridge. As Zeta and Megatron dueled, both ships were hurled into an unstable space bridge through to an unknown planet.