Makluans

The Makluans were a hyper-advanced reptilian civilization native to the planet Oa, and one of the earliest space-faring species in the universe. They were driven to near-extinction by the Celestial Unicron. The survivors became the leaders of the Green Lantern Corps.

Manhunters
The Makluans were one of the first space-faring species in the universe. They created Ten Rings of power. But the power corrupted the first person to use the Rings, Fin Fang Volthoom. The Rings were locked away.

With the number of spacefaring species growing, the Makluans made their first attempt at an interstellar police force. They created genetically modified clones that could shapeshift to infiltrate any species, called Manhunters. But these biological Manhunters proved unable to determine a difference between crimes actually committed, and crimes that they had only detected the intent for telepathically.

Now organized into the Guardians of Oa, the Makluans struck down their creations, and stranded them on a planet called Mars. They tried again, this time with robotic Manhunters. This attempt proved much more successful. But against the Celestial Unicron, the Manhunters weren't enough. The vast majority of the Makluan civilian population died before Unicron was defeated.

A divide began to display itself within the Manhunter ranks. After Megatronus slaughtered an entire sector of space, the Guardians of Oa deposed the Manhunters as peacekeepers, and banished them to a largely uninhabited region of space.

Lantern Corps
The Guardians of Oa tried again to create their perfect peacekeepers, this time returning to the concept of Rings of power. They forged Rings that channeled seven aspects of the Emotional Spectrum, and gave them to local lifeforms that would be best suited to use them. But the different kinds of Lanterns proved too disparate to work together, and the Corps split. The Guardians of Oa chose to remain with the Green Lantern Corps after the division.

After eons of atonement, Fin Fang Volthoom was given the chance to prove himself once more, by hiding the ten Rings that had previously driven him insane. He did so, such that no-one except himself would know their locations. Much later, Fin Fang Volthoom was tricked into retrieving the Rings, by a human of earth named Temugin Saki.

Technology
Makluan technology is characteristic in that it frequently compounds with itself. Related pieces in a set, when working it tandem, will become vastly more powerful and versatile than the individual devices working separately.

The most dramatic example of this property is the set of ten Makluan Rings, referred to as the Mandarin Rings. When all wielded at once, they grant reality-altering power that rivals that of the Infinity Stones. Other examples of this would include Voltron, and the Masks of Power forged by Makuta.

The Makluans also frequently worked with the Emotional Spectrum. Most notably, the Rings wielded by the various Lantern Corps. The Manhunters could also detect and use this energy. The Makluans are also notable for being one of the few civilizations to achieve technological divinity, much like the Asgardians did, through the invention of one of the Mandarin Rings.

Survivors
Guardians of Oa

Fin Fang Volthoom

Larfleeze

See Also:
Makluan (race), on Iron Man Armored Adventures Wiki

Guardians of the Universe, on Green Lantern the Animated Series Wiki