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For the comic, see Planet Killer (comic).

A doomsday machine

A doomsday machine firing its antiproton weapon

Doomsday machines or planet killers were incredibly powerful, ancient robotic weapons, which were encountered by the Federation on a number of occasions.

Origins and specifications

It was believed the doomsday machines were created by the Preservers to be used against the Borg. Though it also seems they may have been unsuccessful and that the Borg, who designated them "Species 4672", were able to vanquish the creator race. (TNG novel: Vendetta, VOY - Planet Killer comic: "Ultimate Weapon")

Doomsday machines featured a neutronium hull capable of resisting many known types of weapon fire. (TOS episode: "The Doomsday Machine") The only weapon known to damage a doomsday machine was the quantum torpedo, with a cluster fired down the maw being capable of destroying it, though it should be noted that this particular machine was a construct of Trelane's and not an authentic doomsday machine as well as being unable to feast on planets to heal and power itself. (ST - The Q Conflict comic: "Issue 3")

The super-dense hull even allowed the vessel to survive within a star. This same hull also generated a disruptive signal that prevented transporters from beaming people into the ship, though transportation was possible, if permitted by the pilot, who was locked into a crystalline "stasis chamber", and merged with the ship. After being locked in, the pilots were not alone; planet killers also contained an intelligence within their cores known as the Many, or the One Voice, which seemed to be a repository of the creators' "souls", or a computerized version of their minds. The Many served as the guiding force of the vessel, however they required a physical, living being to actually unite them in purpose.

Doomsday machines required a constant "diet" of planets to maintain their peak performance. This need to consume planetary matter was believed to be part of the machines' design to destroy planets the Borg had assimilated. The matter obtained from planets, or other targets, such as Borg Cubes, increase the ships' power reserves and even allowed them to repair themselves.

Doomsday machines were equipped with a devastating antiproton beam even the Borg were incapable of resisting. These ships had a powerful tractor beam, which was used to drag either starships or planets into their maw.

Despite their powerful defensive and offensive abilities, doomsday machines were generally slow compared to other starships. Nevertheless, they were, in fact, capable of achieving warp 10, though this appeared to be a rarely used ability. (TNG novel: Vendetta)


Some sources hold that the machines were built 50,000 years before the Federation's encounters with them, and that a thousand years later, a wave of the weapons led to the destruction of the First Orion Empire. (Last Unicorn RPG module: All Our Yesterdays: The Time Travel Sourcebook) However others claim that the machines were billions of years old, and came from outside the galaxy, a theory that Jean-Luc Picard did not buy into due to the lack of planetary bodies in the intergalactic void. (TOS novel: Star Trek 3, TNG novel: Vendetta)

All Our Yesterdays implies the Doomsday machines were responsible for the destruction of the First Orion Empire, but it only says "robotic planet killers". The Decipher RPG module: Worlds extends this to "robotic planet-killing craft from another galaxy."

Another account postulated that the doomsday machine was created by a race of giants from another galaxy at war with another race over three million years ago. The Creators turned their weapon on their enemies' homeworld, the machine's might utterly destroying it. When it returned home however, the weapon malfunctioned and destroyed its creators' home before turning on the other planets of the solar system. After a thousand more systems had been destroyed, the doomsday machine's path carried it outside its native galaxy where it finally shut down, content to drift until more food could be found. Some survivors of the machine's previous attacks had been hunting only for all but one of them to abandon their pursuit when faced with the intergalactic void. The machine eventually reactivated in the Milky Way Galaxy but was, at this point, far weaker than it had been in its prime, time and gravity having stolen much of its destructive power. (TOS - New Visions comic: "Cry Vengeance")

First contact

The USS Constellation engaging the doomsday machine.

The Federation's first encounter with a doomsday machine occurred on stardate 4202.1 when the USS Constellation under the command of Commodore Matthew Decker was investigating devastation within System L-374. As the ship entered the system, they discovered the fourth planet in the system was collapsing. In orbit, a doomsday machine was firing its anti-proton beam, preparing the planet for consumption. As the Constellation approached, it was attacked by the planet killer, deflector shields giving no defense. Counter-attacks could not pierce the ship's neutronium hull and the Constellation was heavily damaged.

Unable to escape, and with the Constellation incapable of calling for aid (thanks to the doomsday machine's dampening field preventing communication, and draining the ship of power), Commodore Decker ordered an evacuation of his crew to the third planet in the system while he, himself decided to remain aboard until the rest of the crew were safely transported. Unfortunately, the doomsday machine soon returned and attacked again, knocking out the Constellation's transporter and thus stranding Decker on the ship; it then moved on to consume the third planet, and Decker could do nothing but watch and listen helplessly as his crew of 400 were consumed along with the planet.

The planet killer's continuing destruction attracted the attention of another Federation ship, the USS Enterprise under the command of Captain James T. Kirk, who managed to receive a faint distress call from the Constellation. Recovering Decker and quickly learning of the futility of attacking the ship, the Enterprise crew were able to calculate that the course of the planet killer which would lead it towards the more densely populated regions of the Alpha Quadrant, including the Rigel system.

Upon encountering Enterprise, the doomsday machine fired upon the ship with its anti-proton beam, knocking out the transporter, communications and damaging other systems. The doomsday machine then disengaged, resuming course for the next star system - which would be the Rigel system. Spock decided to get back to the Constellation to retrieve the landing party, so that they could escape the subspace jamming to inform Starfleet Command.

With Kirk off the Enterprise, Commodore Decker had the authority to assume command of the Enterprise, and ordered that the Enterprise needed to engage the Doomsday Machine. When Spock refused, Decker relieved Spock of command. He then attempted to attack the doomsday machine with the Enterprise. This attack (again) proved futile, and Enterprise was heavily damaged in the attack. The Enterprise was nearly dragged into the planet killer's maw, but Kirk was able to save the ship, by having the Constellation fire upon the doomsday machine, distracting it long enough to allow Enterprise to escape.

Communications were restored between the two ships shortly afterward. Captain Kirk refused to allow Commodore Decker to wreck his ship, and had Spock relieve him of command. While being escorted to sickbay, Decker overpowered the guard escorting him, and stole the shuttlecraft Einstein. Decker flew the shuttle directly into the planet killer's maw. The shuttle exploded within the planet killer; however this also registered a small power loss on the Enterprise scanners.

At this point, Kirk and Spock determined that a larger explosion inside the planet killer might probably destroy the internal workings of the device. Chief Engineer Scott rigged the Constellation's impulse engines to explode. and Kirk took the Constellation inside the planet killer, and when her impulse engines overloaded; the resulting explosion destroyed the internal workings of the planet killer. Kirk was beamed off the ship narrowly before this. (TOS episode: "The Doomsday Machine")

The SS Charles Darwin soon arrived to study the doomsday machine only to be destroyed by a craft piloted by one of the machine's creators. When the Enterprise confronted the alien, he revealed both his origins and that of the weapon before his overworked engines exploded, killing him. (TOS - New Visions comic: "Cry Vengeance")

The remains of the planet killer were shipped to a secret Starfleet facility known as The Yard, where it, (and other alien technology), was studied by a team of scientists-including Dr. Pad. (TOS - Constellations short story: "Devices and Desires")

Eventually, the remains were returned to the Rigel system to act as a monument in honouring those who lost their lives in its destruction. (VOY - Planet Killer comic: "Death")

Sometime later, the planet killer was moved to Epsilon Sigma V, informally known as "Trophy World", where it was converted into a Starfleet Museum. (TNG novel: Before Dishonor)

A doomsday like any other

(FASA RPG module: A Doomsday Like Any Other)

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The third time a planet killer was encountered was by the USS Enterprise-D when one was being used by a woman called Delcara; she used a theory (developed by Jean-Luc Picard in his years at Starfleet Academy) that the machine's creators had hidden their weapon only a short distance outside the galactic barrier (Picard reasoning that the machine's power demands were too great for it to have simply drifted through the barrier via sheer inertia) to locate such a weapon. Based on its more advanced design, including additional weapons beyond the prime weapon, it was speculated that this was the final version of the planet killer weapon where the one encountered by Kirk's Enterprise was just a prototype.

She used the weapon on a crusade to destroy the Borg in revenge for their assimilation of her people. Her first, major engagement was against a Borg Cube that had ravaged the planet Penzatti. This resulted in the Borg bringing a further two vessels to combat this "new menace." This did not seem to trouble Delcara, who was intent on using the weapon to destroy her enemy, regardless of the fact that this would result in the destruction of countless planets on the way to Borg space. Her path meant that the planet killer would travel through Tholian space, which resulted in the Tholians attacking the doomsday machine with a Tholian web, to no avail. The Federation attempted to neutralize the threat Delcara posed and during negotiations the Borg attacked with their two cubes. The assault was almost successful, as the Borg managed to crack the neutronium hull of the ship and beam in a boarding party. However, this attack was repulsed by Commander Riker while Picard and Guinan attempted to negotiate with Delcara, Riker reasoning that the Borg were a far more immediate threat despite the moral dilemma posed by the doomsday weapon's existence.

One of the cubes was destroyed by three Starfleet ships that were at the location, and the second was destroyed by the planet killer. The doomsday weapon consumed the cube to repair and refuel itself, then left at warp factor 10 to reach Borg space before its pilot expired from her injuries sustained from the Borg raiders. Both she and the craft were trapped in an infinite-mass time loop, spread to every point in the cosmos. (TNG novel: Vendetta)


In 2375, another doomsday machine was encountered by the starship USS Voyager on its journey home through the Delta Quadrant. An ex-Borg member of the crew, Seven of Nine, was aware the Borg had failed to assimilate the technology, having no defense against it. Nevertheless, Voyager attempted to destroy the weapon, in order to stop it from cutting a swath of destruction. Ensign Harry Kim attempted to use the same tactic that destroyed the original planet killer, using the damaged ship of an alien they had recently rescued, but this failed. A second attempt at infecting the weapon with a Nanoprobe virus also failed because of the strong hull of the ship, but this strategy was successful when applied directly to the ship's internal systems. When the planet killer was distracted by Voyager, Tom Paris took the Delta Flyer and beamed The Doctor into the ship- his mobile emitter coated with a thin layer of neutronium so that the planet killer's sensors would have trouble distinguishing the emitter from itself-, who administered the microscopic weapon. (VOY - Planet Killer comics: "Ultimate Weapon", "Old Tricks", "Death")

Trelane's planet killer

In 2379, Q abducted the command crews of James T. Kirk, Jean-Luc Picard, Benjamin Sisko, and Kathryn Janeway to serve as proxy armies. In their second challenge, Trelane conjured up a doomsday machine and turned it on the four ships. Though initially overwhelmed by the monster's power, the crews soon found it was vulnerable to quantum torpedoes, allowing them to destroy it by firing a salvo down its maw. (ST - The Q Conflict comic: "Issue 3")


Following the invasion of the Alpha Quadrant by the sentient Borg supercube, the crew of the USS Enterprise-E proceeded to the Starfleet Museum in an effort to restore the originally-discovered doomsday machine for use against the Borg. An away team, consisting of Ambassador Spock, Lieutenant Commander Geordi La Forge and Seven of Nine boarded the craft, searching for a way to restore the device to working order. While working to reactivate the device, its AI confirmed that the craft was built as a weapon against the Borg Collective. Its original pilot was killed during the destruction of the USS Constellation. Seven of Nine offered herself to the weapon and became Seven of One - "the master" of the weapon. Launching the craft, the doomsday machine engaged several Borg vessels and the cube containing the Borg Queen. The weapon was absorbed by the Borg and destroyed during this engagement. (TNG novel: Before Dishonor)

The Proto-Prototype

Having begun a new mission of exploration in the Odyssean Pass, the Enterprise-E soon made contact with the Raqilan of Henlona and the Golvonek of Urphrel, two races who shared the same star system and had been at war for decades. When the Enterprise arrived, they discovered a ship known as the Poklori gil dara, or Armageddon's Arrow, capable of destroying planets with a particle beam weapon, sent to this time period after it was constructed by the Raqilan in the future. While Commander Worf and Lieutenant Dina Elfiki investigated the solar system in the shuttle Siouxsie, they discovered a version of the doomsday machine that had crashed into one of the solar system's moons, soon identifying it as a more primitive version of the machines encountered by the Federation in the past after mistaking it for the prototype version of the Arrow. Worf and Elfiki concluded that the Raqilan had discovered the crashed planet killer and would spend the next few decades developing their own version of it, which would eventually become the Poklori gil dara. The timeline was altered when the surviving Raqilan crew decided to crash the future ship into the moon where its past self was being constructed, destroying both versions of the Arrow. Having contacted the Federation, Picard was informed that teams would soon arrive to retrieve the crashed prototype planet killer from the moon, noting that scientists would be grateful for the chance to study such remarkable technology once again. (TNG novel: Armageddon's Arrow)

25th century

The Doomsday Machine, as it appears in 2409.

in 2409, during the Klingon war with the Federation, the Klingons under B'Vat got hold of the Doomsday machine after he was aided by the temporal manipulations of the Na'khul. This race informed him of the existence of the weapon in the T'Ong Nebula where he uncovered it and intended to use it to bring about the ascendance of the Klingon Empire. After relocating it to the Imaga system, B'Vat intended to use the planet killer to destroy a Federation world in order to further hostilities between the two powers. The same system was used by the Empire to stockpile devastating torpedo weapons. B'Vat's plan would come to an end when his own aide, K'Valk, notified Starfleet of this plan leading to one of their vessels confiscating the weapons there whilst a Federation fleet battled the Klingons along with the doomsday machine. By using the Klingon torpedoes, the Starfleet vessel was successful in destroying the planet killer once and for all. (STO mission: "The Doomsday Device")

Mirror universe

In the mirror universe in 2293 as it journeyed through Klingon space, on its way towards the Klingon homeworld of Qo'noS, the machine left a trail of destruction. It was escorted by warships from the Terran Empire that attempted to use the automated machine as a weapon against its enemies.

The ISS Excelsior arrived on the scene, where Hikaru Sulu attempted to help the Klingons (as he and his crew had accidentally exchanged places with their mirror universe counterparts). During the struggle, the IKS Kronos One plunged itself into the weapon's path, sacrificing itself to destroy it. Another two K't'inga-class vessels, the IKS Bortas and IKS Q'ud, did similar actions in reducing the ship's firepower to 25%. Excelsior then aided the Klingons by disabling an Imperial Starfleet vessel. The ISS Kodos, an old Constitution class warship, was forced into the planet killer, which was disabled as its internal structure was damaged. (TOS video game: Shattered Universe)

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