Infinity Gems
The Infinity Gems was extremely powerful gems containing the ability to control Time (orange), Space (purple), Reality (yellow), Mind (blue), Power (red), and the Soul (green). They were apparently once part of a being of infinite power, known as Nemesis, that lived before existence- but lived alone. It supposedly destroyed itself from loneliness, leaving the Gems- and all realities- as its remains. Its sentience remained as the Ego Gem- which was separated from the others for a time. The other Gems were originally scattered across the universe. The mad Titanian Thanos gathered the Infinity Gems together once into a weapon, with which he planned to destroy the universe- he was stopped by [Adam Warlock], at the cost of Warlock's- and Thanos'- lives.
The Gems were given to five of the Elders of the Universe- the Time Gem to the [Gardener], the Space Gem to the Runner, the Reality Gem to the Collector, and the Mind Gem to the Grandmaster. The Soul Gem was an exception, granted to the [In-Betweener]. Thanos, resurrected from the dead by Mistress Death, confronted these guardians and gathered the Infinity Gems once more, forming them into the Infinity Gauntlet.
With absolute power over all existence, Thanos slew half of the universe's population to please his mistress. A force of superheroes attacked Thanos, but he defeated them all- this was followed by a force of cosmic beings, including Eternity himself. Thanos barely defeated them, becoming one with the universe- but leaving his physical body vulnerable, allowing Nebula to take the Gauntlet for herself. Less experienced in its power, Nebula was attacked by the remaining heroes and cosmic beings, while the resurrected Adam Warlock used his connection to the Soul Gem to disrupt the Gauntlet from within, taking it for himself.
Eventually, Eternity petitioned the Living Tribunal to prevent the Gems from being used in unison again, and Warlock eventually agreed to this decision. He formed the Infinity Watch, giving the Gems to Gamora (Time), Pip the Troll (Space), Moondragon (Mind), and Drax the Destroyer (Power). He kept the Soul Gem for himself, and entrusted the Reality Gem (secretly) to none other than Thanos. The Gems were reunited briefly by the Magus, when the Tribunal's edict was temporarily lifted, but the Reality Gem was not part of the equation and the Magus was defeated through that deficiency. The Infinity Gems were given back to their owners again.
Sometime later, the entity known as Rune, who hailed from another reality, took the Gems from the Watch and attempted to use them together himself. The Living Tribunal detected this, and sent the Silver Surfer to battle Rune. The creature, unused to the infinite, was defeated, but the Gems were scattered across Rune's home universe. Warlock disbanded the Infinity Watch and went into Rune's reality to retrieve the Infinity Gems.
The Gems temporarily merged with the Ego Gem to reform Nemesis, which temporarily created the Sketch World (a pocket dimension combining elements of Rune's "Ultraverse" with Earth-616). Nemesis was destroyed by the combined forces of Ultraforce and the Avengers, shattering the link between the gems. They split into individual beings, and the Reality and Time Gems worked together to stabilize- if not undo- the warping effects Nemesis' power had on the Ultraverse.
