In their initial appearance, the Controllers came from "another space-time continuum." Their universe had almost been destroyed by war, and they were determined to prevent the Earth-One universe from going the same way. They used their mind-control abilities to prevent intergalactic war, but also had powerful weapons, including the Sun-Eater. This concluded with "The Death of Ferro Lad" story where Ferro Lad dies destroying the Sun Eater.
The Controllers' origins were changed following the Crisis on Infinite Earths events. They were now originally part of a race of immortals called the Maltusians. These beings left Maltus and colonized a new world called Oa. Now calling themselves Oans, they feel responsible for the catastrophic effects on the universe caused by one of their own, the renegade scientist Krona. The group argues over ways to handle the situation. One group of Oans desires to dedicate their immortal existences to contain evil. This group eventually became the Guardians of the Universe. Another group decides that evil should be destroyed. This group leaves planet Oa, eventually becoming the Controllers. It is also revealed that the Controllers left over the Guardians' decision to not destroy their former robot minions, the Manhunters, after the Manhunter rebellion on Oa.
Controlling The Darkstars
The Controllers eventually recognized the benefits of having a law-enforcement agency at their disposal and formed the Network for the Establishment and Maintenance of Order (NEMO). Their agents were the Darkstars, armed with crimson exo-mantle that was powered by the Controllers' own energy. Many former members of the Green Lantern Corps joined the Darkstars after the Corps was destroyed. As time went on, the Controllers expressed concerns about the effectiveness of the Darkstars. More specifically, they were troubled that Darkstar agents were mostly looking after their own agendas rather than those of the Controllers. They withdrew their support from the Darkstars. This made many of the early Darkstar uniforms useless, as they relied on energy transmitted from the Controllers. The Darkstars are now defunct; most had been slain by the forces of Grayven.
In their continuing effort to create an alternative to the Green Lantern Corps, the Controllers experiment on Martyn Van Wyck, transforming him into the pyro-kinetic Effigy. Their plans to create an entire organization of such beings, all brainwashed to serve the Controllers, was underway before Kyle Rayner learned of the plan and convinced the immortals to abandon it. An unnamed Controller was featured in Power Company issues #12-14, where he is a prisoner of Doctor Polaris. The Power Company eventually succeeds in freeing him. He tells the group that his original reason for visiting the Earth was an attempt to re-secure a cosmic artifact called the "Mephistopheles Matrix."
In the series, Trinity, a group of Controllers discover a Krona freed of his Cosmic Egg and aid him; though, when their treachery is discovered by Krona they are promptly eliminated.
In the Final Crisis storyline, the Controllers were revealed to survive into the 29th century, at which time they develop the Miracle Machine, whose schematics Superman memorizes upon a visit to the 31st century.
In the Blackest Night storyline, a small group of Controllers appeared in search of the "orange light of avarice," hoping to create their own Corps. This group locates the orange light on the planet Okaara, but they are slaughtered by Larfleeze, and assimilated as constructs in his Orange Lantern Corps.
The Controllers are immortal, like all Oans. They can manipulate energy and create vast technology and weapons. Their most known weapons are The Sun-Eater, The Miracle Machine, and The Darkstar exo-mantle.
In the future of the Legion of Super-Heroes, a renegade Controller became the villain known as the Time Trapper. Various DC Comics reboots have since altered this timeline, which is one of many origins given for the Time Trapper. The Controllers also ended up giving the Miracle Machine to the Legion for safekeeping.
In other media
A Pre-Crisis Controller appears in the two-part Legion of Super-Heroes episode "Sundown" voiced by David Lodge. This renegade Controller believes that the ultimate perfection comes from chaos, rather than order, and releases the last Sun-Eater to spread this chaos. Superman was sent to stop him on his own while the Legion stops the Sun-Eater. The Controller's plan was foiled, but at the cost of the Legion member Ferro Lad's life. As he makes his escape, Superman warns him to never appear again.
The Controllers briefly appear in the Batman: The Brave and the Bold episode "When OMAC Attacks." Batman alongside Hawk and Dove had to stop a war between the Controllers and the Warlords of Okaara.