Originating as the Quintessons' Dark Guardian robots, the Guardian robots of the Golden Age of Cybertron were powerful giant blue robots that kept the peace. They gave the Decepticons much trouble during the early days of the war but were eventually overcome.
Only one, Omega Supreme, the Guardian robot of the Crystal City, was ever named, had a distinct color scheme, and was shown to be sentient or able to transform, but it was not revealed if he was indeed unique amongst them in those regards.
- Japanese name: GADEP
At the end of Cybertron's Golden Age, the Guardian robots fought against the newly assembled Decepticon army extensively and destroyed quite a few drone warriors. They gave Skywarp the creeps with Thundercracker stating that they gave them a "pounding" in the old days. Shortly before Megatron's first confrontation with the newly activated Optimus Prime, a Guardian's head was destroyed by Decepticon laser fire, deactivating it.
Millions of years later, after escaping an Autobot attack on their time machine facility, the Decepticons found the remains of the damaged Guardian robot. Shockwave managed to reassemble the giant, though he noted that the lack of a head would limit its maneuverability, to which Megatron commented that "A warrior doesn't need a head, just a good strong body." This Guardian was unleashed upon Optimus Prime and the Autobots until the Aerialbots arrived from the past and merged into Superion. The sheer strength of the Guardian overwhelmed Superion at first, but he retaliated to such an extent that the Guardian was thrown into the air before crashing back into the ground where its body was destroyed.
While creating a time window to the past, to stop the Transformer revolt, the Quintessons were discovered by a band of Autobots. Blaster, Blurr, Perceptor, Ramhorn, Rewind and Wreck-Gar attacked the Quintessons forcing them to withdraw leaving the portal open. When Quintesson reinforcements emerged, Blaster, Blurr, Ramhorn, Rewind and Wreck-Gar escaped through the window, while Perceptor was left behind. While they went in, an ancient Autobot calling himself A-3 came to the present. The group of Autobots were promptly attacked by Guardian Robots only to be saved by a female Autobot warrior named Beta. She was a leader of a rebel army set to attack their oppressors, the Quintessons. There were two problems: the Autobots were not warriors but engineers and scientists, and their primary leader A-3 had disappeared. As the time travelling Autobots aided the Autobot rebels, A-3 returned just in time to use his Coda Remote device that promptly deactivated the Guardian robots allowing the present day Autobots to go through the time window to their home.
Dreamwave comics continuity
Known as Omega Sentinels, these massive mechanoids were seen guarding various strategically vital locations in Iacon. During the Decepticon attack on Iacon, they were among the first and last lines of defense standing between the Decepticons and the Decagon. Shockwave managed to kill two Omega Sentinels during the battle.
With one shot.These versions bore a much closer resemblance to Omega Supreme.
- Toshi Boei Robo GA(-)DEP (2008)
- Japanese ID number: 64
- Accessories: 2 small shields, 2 medium shields, 2 large shields, 4 armour halves (A, B, C, D), 4 ankle half (E, F, G, H), 2 feet, backpack, 4 tracks (J, K, L, M)
- An e-Hobby exclusive, this toy is a redeco of the Generation One Omega Supreme toy. Using the same tooling as the Encore reissue Omega, this toy features the same retooled head.
- The Guardian transforms into three individual components simultaneously: a large rocket base, a rocket and a tank. Not unlike the Seekers, whose toys involve minimal actual transformation and more "pull all the bits off and put them back on in different ways," the Guardian robot involves next to no actual manipulation of the parts, "transforming" instead by being disassembled into its component pieces, which are then put back together in a different configuration.
- The Guardian's distinctive forearms (left large cannon and right large, three-fingered claw) disconnect from their arms at the elbow and plug together end-on-end to form the rocket. Its legs are comprised of quite a few independent parts; the outer casing of each one is a "shell" made up of two pieces held together by three sliding yellow clips, concealing two further "shell" pieces which clip around the leg proper and are held together by its feet. All of these parts are removed and reassembled to form the "core" of the rocket base, which is completed with the addition of the Guardian's backpack and feet as a gantry for the rocket to stand astride, and its wings (made up of six individual pieces themselves, which can be assembled in various configurations) as a roughly elliptical track that surrounds the whole affair. This leaves the Guardian's torso, which then undergoes some actual transformation to become a tank that rests on the track. The torso features a battery-operated motor which propels the tank around the track as its turret spins and flashes with orange light, or allows the Guardian to walk (very slowly) forward in robot mode. This motor is extremely susceptible to failure.
- Although no toy of the Guardian Robots was made during the original Generation One toyline, they are clearly a slightly more Dery-ized, bulkier version of Omega Supreme. So much was this similarity that it came to pass 20 odd years later with the e-Hobby exclusive above.
- The first homage or representation of the Guardian Robots came in the form of Energon Omega Sentinel, a recolor of Energon Omega Supreme (himself an homage to the original Omega Supreme), featuring a similar blue color scheme.
- ↑ 都市防衛ロボ ガデプ (Toshi Boei Robo Gadepu), translated as "City Protection Robo GADEP". GADEP is short for "Groundling Auto-DEstruct Powerbroker".  This is a retconned acronym. Originally, it stood for "Guardian/Defender/Protector" (Gādian Defendā Purotekutā), but this was more implied than explicit, giving the new acronym even more priority.