This is the Amalgam Universe combination of a Guardian of the Universe (DC)and Uatu the Watcher (Marvel).
Uatu the Guardian is a member of one of the oldest races of beings in the universe, dating back to its origins. They posses vast cosmic powers, but have taken a vow not to intervene with the dealings of the universe.
It is possible that these Guardians have some connection to the hero Iron Lantern, or Oa, the Living Planet.
It is also possible that there exists a rebel Guardian who works in conflict with the others, just as DC's Guardians have one rogue, Krona, and Marvel's Watchers have the rogue Watcher Aron.
Uatu is also responsible for framing Hal Jordan for killing Sinestro, a fellow member of the Starbrand Corps. While the Corps searched for Hal, Uatu killed the other members one by one, leaving Hal the last. But when he tried to kill Hal, he was met by the Speed Demon, who seemingly destroyed him for his crimes. Uatu survives and later claims to have regained his sanity.
It is Uatu who warns the Challengers of the Fantastic of the coming of Galactiac to Earth, thus breaking his vow of non-interference. Uatu sent one of Johnny 'Red' Storm's stormtrooper clones inside of Galactiac that was controlled with Johnny's mind. From the inside, Galactiac was defeated.