Galactus possesses cosmic power beyond most forms of measurement (The Power Cosmic). He can levitate; restructure molecules; convert matter into energy and vice-versa; project energy with enormous concussive force; teleport himself, others, and objects across space, dimensions, and time; erect virtually impenetrable fields; restore others from any injury, even total disintegration; and endow or enhance powers within others. Even his heralds, imbued with the smallest fraction of his power, can manipulate matter and energy far beyond human comprehension. Though he generally avoids physical conflict, Galactus can bolster his own strength beyond any known system of measure. Galactus is telepathic, able to scan the thoughts of virtually any known being.
To sustain his immense power, Galactus requires energies derived from a biosphere, a planet able to sustain living beings, though life does not actually have to be present. Though Galactus can extract and absorb this energy himself, he generally employs his immense Elemental Converter to perform the process, as it is far more efficient and avoids the expenditure required of him. Sometimes the planets on which he feeds are left barely habitable; other times he consumes all life and water, leaving it devastated and barren; most often the process reduces the planet to space rubble. When Galactus was newly formed, the energy of a medium-size Earth-like planet sustained him for over a century. Now he needs to feed about once a month; in addition, when preparing for a massive expenditure of energy, he may absorb planets more frequently to amplify his power stores. Conversely, when he does not feed within his allotted time, his energies will dwindle, and he will even begin to physically shrink as they drop dangerously low. His body totally converts the energies he absorbs for his life functions and activities without any waste products.
Though seemingly destroyed on several occasions, Galactus is always restored to full power eventually. In addition, despite being a physical being, Galactus can adopt a manifestation (M-Body) from the Dimension of Manifestations in order to commune with abstract beings, such as Death and Eternity.
http://marvel.com/universe/Galactus
Proteus is a mutant that possesses a vast psionic ability to manipulate and alter reality. He existed in a state of pure psionic energy and could take possession of human bodies that his energies eventually "burned" out, killing them (including his own original body). Proteus also possessed telepathic abilities. His reality manipulation powers allow him to transmute matter and bend the laws of physics according to his imagination within a certain distance. Using this power he can easily turn a building into liquid, turn a vehicle into bees that attack at his mental command, transform energy into matter, manipulate weather, or strip a person of their mutant powers. He often reverses local gravity, opens fissures in the earth, and stretches people painfully into liquid shapes (they return to normal when he no longer concentrates on manipulating their bodies). Use of this ability tends to speed up the rate at which his body will burn out. Proteus' reality warping ability is contingent upon line of sight: if he shifts his sight to another object and warps it, the previous object he was warping will return to normal.
Proteus can enter and completely possess another living being. Only beings with metal in their bodies appear to be immune. The bodies of most beings burn out within hours or a few days, although a few have been known to last longer. Proteus can leave a body before it is destroyed, but he usually does not. No possessed person has been shown able to resist or break free of Proteus' domination. Proteus has access to all the memories of his host while he possesses them and after he has left the body. Proteus has occasionally exhibited some telepathy, perfect recall, and the ability to mentally download computer information. After his revival through Destiny during the events of Necrosha, Proteus is shown to be able, to his surprise, to possess multiple individuals simultaneously.
Proteus can become a being made of energy at will. He will also do this automatically whenever his body burns out so badly that it disintegrates. The ability to possess a new host and to manipulate reality is greater in this form. However, it is more vulnerable to the touch of metal. Contact with enough metal in this form can disrupt Proteus' energy and destroy his consciousness, dispersing it. It is possible for his consciousness to reform after such a disruption, but he has not shown the ability to do so without assistance. Proteus has at times exhibited the ability to transport himself inter-dimensionally, but it is not known whether he always could do this, or his resurrection by the Scarlet Witch enhanced his powers, or if he needed to use a connection to the Panoptichron in order to accomplish this.
http://en.wikipedia.org/wiki/Proteus_%28comics%29
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