There are many strange energy sources in the universe; these are only some of the (slightly) better known ones.
The Power Cosmic
Galactus is both the wielder and the source of the Power Cosmic, which allows him to accomplish almost anything he desires. He can manipulate matter, travel across time and space, and even destroy worlds with a thought. His Heralds, some of the most powerful beings in the galaxy, have access to just a fraction of Galactus’ power.
The Opposing Force
This energy seems to be the Negative Zone’s equivalent to the Power Cosmic. It has a strange and corrupting effect on this universe, and users seem to channel it through the bizarre creatures called Currs rather than accessing it directly.
Dark energy is a form of energy that permeates all of space and tends to accelerate the expansion of the universe. A small number of unique beings have the ability to harness and control dark energy.
The Nova Force
The Nova Force is a near-limitless source of energy first harnessed by the Xandarians. This energy is controlled and kept under check by the Worldmind. Nova Corps members can use the Nova Force in many ways, including flight, personal augmentation, gravity control and even opening small stargates.
The Quantum Zone
The Quantum Zone is a dimension of limitless potential energy that lies behind this one. Unique tools called the Quantum Bands, created by Ego the Living Planet, allow the user to travel through and draw energy from the Quantum Zone. The Quantum Bands are currently owned by the human Wendell Vaughan, aka Quasar.
A number of civilisations have learned to channel and contain cosmic energies into cubic matrices, and these objects are highly sought-after items of power. It’s possible for Cosmic Cubes to become sentient; one such cube transformed itself into a near-deity called the Shaper of Worlds, and later turned a human artist into the demigod Glorian.
The cosmos is not a place without faith. Many races maintain belief in holy or supernatural forces, and many of those beliefs have proved to be true in some fashion. Those who master and control magical forces are very uncommon, but they do exist and can perform acts that even advanced science cannot mimic or predict.