Avatars are an ancient group of magical beings who can bend the very fabric of time, space and reality. Their power is often described as the ability to manipulate time and space, through which they can reverse time, and even create alternate realities. Unlike witches, warlocks, demons, Whitelighters, Elders, and other forms of magical beings, their power is said to be nearly unlimited and completely unconstrained by good or evil. Thus, Avatars are not categorized as good or evil, but neutral, "beyond the limits of good and evil". Their desire is to shape the world to their own design making it a perfect world and will do anything in order to keep Utopia safe and without violence. This includes taking away free will as Leo noticed. Avatars exist outside of time and space.
At one point in time, it appears that Avatars either ruled over the entire world, or that they tried to impose their will in the past, but the magical community revolted, and good and evil working in combination created a very powerful potion with which to destroy them, in order to allow free choice. The threat of this potion alone, was enough to force the Avatars to withdraw. Unlike most magical creatures in the Charmed universe, Avatars are magically connected to each other. If one member of the collective Avatar dies (and it is stated that no Avatar has ever died in the past), it affects all Avatars, making them weaker and less powerful both individually and as a group as demonstrated when the Avatar Beta was killed by Kyle Brody with a potion. This had similarly been applied to the Charmed Ones and later to the Triad.
In Charmed, the Avatars are depicted as a peaceful, yet powerful collective whose sole purpose is to create their version of Utopia, by putting all humans to sleep temporarily and ridding the earth of all demons/evil beings during the slumber. The Avatars promise that upon awakening, the war between good and evil will be over and humanity can lead peaceful and happy lives. However, the promise of Utopia comes with a very high price: if any person creates 'conflict', that person will be removed from existence by the Avatars, taking away Free Will.
The Avatars made their first appearance in Season 5, when two of them came to Cole Turner and asked him to join their ranks. Cole at first rejected their offer, and attacked them. However, even as powerful as Cole was, his energy balls had absolutely no effect on them, possibly due to their existing outside of space and time; There is also an implication that the Avatars couldn't vanquish Cole either. They possibly wanted Cole's utter indestructibility and self-healing powers added to their powers; That might have rendered them either immune to, or able to recover from, the one potion that could harm them.
In a later episode, Cole (who had sadly gone insane) realized what the unlimited powers being an Avatar might provide him. He agreed to the opportunity and became an Avatar, with the Avatar leader Alpha agreeing in advance that Cole could use completely unlimited powers once for his own purposes (Alpha didn't realize in advance what Cole intended, nor does it appear that Alpha ever really understood the depths of Cole's despair, of Cole's desperation to be with Phoebe, or Cole's madness).
Cole then used his new powers to create a parallel alternate universe or alternative reality for his personal gain, where the Power Of Three was never recreated after Prue Halliwell's death. Cole did this with the belief that an alternate Phoebe, that had never met her half-sister Paige, who had never vanquished him when he was possessed by the Source, would still love him as fiercely as Phoebe in the original reality had, before those events happened.
When Alpha realized what Cole intended, the Avatar leader directly warned Cole (just before Cole cast his spell): "You have no idea what you're getting into. Changing the past to create an alternate reality has unforeseen consequences, Cole. Even for you...". Alpha then appeared in the alternate reality, to Cole's great surprise (Cole apparently cast his spell in a way that would remove anyone's knowledge in any reality of what he had done, but it had no effect upon the Avatars). Alpha then begged Cole to reverse his spell, and he directly warned Cole: "You're not invincible in this reality, Cole. By changing that one critical event, you've changed even more than you see before you... You've changed you". Unfortunately for Cole, Alpha was quite correct; While in the alternate world that resulted from his Avatar spell, he wasn't the invincible Cole, returned from death with many powers acquired from the Demonic Wasteland, nor was he an Avatar. Cole was then governed by the same rules that applied to the alternate dual Cole–Belthazor he displaced; i.e. having "crossed over" and assumed the life that the alternate Cole–Belthazor would have led, while Cole had the same powers as the Cole–Belthazor he displaced, he also was then subject to the very same physical and magical vulnerabilities as Cole–Belthazor, and thus got himself killed (exactly as Alpha had feared he would). 
During Season 7, Leo became an Avatar in desperation, wishing to use the powers to bring Piper and Phoebe back from the dead, and to also prevent the destruction of all reality, that could result from the unending warring of good and evil (he saw this danger in a vision quest, that Alpha had entered into). Leo then placed high faith in the Avatars' dream, seeking to create a better world for all. After that, the Avatars sought and recruited magical help from the Halliwell sisters (this perhaps also as a result of what had happened with Cole; The Avatars also never mentioned Cole to Leo, or to the sisters...). Having long desired a demon-free life, the sisters agreed to go along with the Avatars' plans. Utopia was then created, a new world reality and order under the watch of the Avatars.
Afterwards, Leo checks with the sisters to see if Utopia has met its promises. However, Leo witnesses that the Avatars are maintaining Utopia in an unexpected manner. They are simply removing anyone who creates conflict from existence. Alpha explained that they had modified the way people think, so as to allow people to more easily accept Utopia. Unfortunately some people were beyond hope, and their inner demons began to surface, driving them to cause conflict. This in turn drove the Avatars to deal with the resulting chaos to protect Utopia. Leo asked if they were killing people, but as they said, they simply removed them, vanquishing the one for the sake of the many. They had the obligation to maintain the world they had created, and they wouldn't let anything threaten that.
However, Zankou showed Leo the way to shock the sisters, as they can't feel pain, grief, and mourning. Leo sacrificed himself to the Avatars, creating conflict by battling demons at the party held in the manor. Phoebe realized Leo's dying warning as her power of premonition reminded her of all the losses they'd faced. And from here, she helps Piper remember her loss of Leo, and Paige's loss of Kyle. The sisters meet Zankou and learn of the making of the potions. Zankou found an ancient Egyptian Tomb, with all the drawings showing their history with the Avatars. Anubis, the Egyptian god of rebirth, said "There is a price to pay for Utopia".
Phoebe stated, "But at least with good and evil, people knew what they were dying for". The Avatars then promised to rewind the world to as it was before Utopia was created, and said they would retreat until another time, where the people are ready to accept Utopia.
In a season 8 episode, an Avatar made a brief appearance when Piper called her and an Elder. She demanded an explanation as to why the Angel of Death wanted to take Leo away. The Avatar and Elder didn't have the authority to answer her question. But they give Piper the information of a higher power who looks over the Grand Design, the Angel of Destiny.
The Avatars' abilities limited only by the total power of their collective of members. The abilities shown in the shows follow:
- Alter Reality
- Energy Waves
- Chronokinesis (Control all aspects of time)
- Remove people from existence (In Utopia)
- Illusion Casting
- Power Containing
<ref>tags exist, but no
<references/>tag was found