The Phoenix
The Phoenix Force (a.k.a. Chaos-Bringer | The-End-Of-All-That-Is | Phal'kon | Ravager of Worlds | Starchilde | World Destroyer | Fire & Life Incarnate)
The Phoenix or Phoenix Force is a cosmic entity and the living embodiment of the cycle of life and death.
Throughout galactic history, many species have worshipped it was a deity (it is part of the Shi'ar pantheon, for example), while others have considered it a purely malevolent entity, and still others have classified it a simply being a poorly understood alien species.
Although it can exist independantly, it has the ability to possess individuals, granting them access to its power, but often driving them mad in the process, which is usually understood to be a factor of limited mortal minds attempting to comprehend the divine.
It is capable of ceding dead planets with new life, but it can (and has) also wiped out entire species in an instant. Although hosts are capable of communicating with the Phoenix, via the White Hot Room, its true motivations remain a mystery.
The Phoenix can be killed, at least temporarily, but on its death a Phoenix Egg is created, which hatches into a reborn Phoenix. Whether the reborn Phoenix is the original phoenix or an entirely new being is the subject of considerable theological debate. There is also debate over whether more than one Phoenix exists, but the majority opinion is that it is an entirely unique entity.
In 2018, as part of her quest to ressurect Nebula, Gamora found the phoenix egg that had been buried by Terrax on Birj and hatched it, briefly becoming a host, resurrecting the Fallen Heroes and creating Singularity.
After Singularity forced it out of Gamora, the Phoenix left earth, though not before awakening a new type of metahuman on the planet.