Sentient Cosmic Force

A sentient cosmic force is a form of Background Magic Field with a will of its own. Like a Background Magic Field, it is a pervasive form of Applied Phlebotinum, existing on a planetary or universal scale, that acts as "fuel" for Functional Magic. It is generally not material, existing as an intangible energy or on a spiritual level, though it may have a physical manifestations in areas that act as a nexus or wellspring for it. However, while Background Magic Field is simply an inanimate part of nature, a sentient cosmic force is capable of thinking and acting on its own.

It can favor some people or factions over others. It can communicate, or at least be communed with. It has goals, and can enact plans to further those goals (which may involve picking someone to be The Chosen One). It is rarely described as actually "alive", however -- it is not something that can be spoken to directly. In this way, sentient cosmic forces are generally distinct from deities: while you may meditate and commune with it in a temple, it doesn't actively seek prayer or worship. More plainly, although a sentient cosmic force is aware of events and capable of influencing them, it is not a person.

If a sentient cosmic force is hostile, or even actively evil, then expect it to be a Crapsack World. Of course, it might be too alien to fit any notions of morality that we can understand. The Dark Side exists when the will of a good or neutral cosmic force is corrupted, or as the Evil Counterpart to the good aspects as a necessary counterbalance.

A Sub-Trope of Background Magic Field. May overlap with The Lifestream when it's created by life itself or when things become one with it after death.

Anime and Manga

 * The Counter Force in the Nasuverse. It favors two sides, "Gaia", the will of the planet, and "Alaya", the will of humanity. If one becomes closer to destruction, the Counter Force will act towards saving the one closer to destruction, usually at the expense of the other. The form it can be communed with exists as "Counter Guardians", heroes who have formed a contract with the World to save it when it comes closer to destruction.

Comics

 * The Source from Jack Kirby's New Gods.
 * The Phoenix Force and the Power Cosmic are two Marvel Universe examples, although the former is hard to explain due to countless revisions.

Literature

 * Dust, from His Dark Materials: while the "magic" element of it is subtle, it's observed to be attracted to children as they reach puberty, and is the reason Lyra's truth-telling Alethiometer works.
 * In The Belgariad, destiny/the will of the universe is both sentient and rather snarky.
 * The god of Mijak from the Godspeaker Trilogy is a particularly evil variant. It never speaks in words to its worshippers, but influences their thoughts and desires and acts through its priests, the godspeakers, and through specific chosen ones like Hekat and later the Hammer. It demands constant sacrifice to sustain itself and very much wants to conquer the world. A character from outside the Mijaki culture at one point describes it as "a well of dark power".
 * JRR Tolkien's Middle-earth is created and sustained by the Flame Imperishable, which emanates from Eru Ilúvatar himself.
 * Magic in the Discworld series is explicitly mentioned to be a little bit alive. It's the reason HEX seems to add or upgrade parts of its own accord, and part of the reason that not using magic is one of the most important skills a wizard can utilize.
 * The True Source, which turns The Wheel of Time.
 * Mistborn has Ruin, the malevolent cosmic force that apparently has power over the mists, and can force them to block sunlight from crops. It was this power which originally threatened the world and was known as the Deepness.It is later revealed that
 * Word of God and other works in Brandon Sanderson's multiverse expand on this further-.
 * To an extent, Yog-Sothoth is this. Yog-Sothoth is often described as The Gate and The Key. It acts as a kind of manifestation, separate entity and integral part of the universe itself. It's two major actions of Lovecraft's works are it  and in the epic Mind Screw that is Through The Gates of the Silver Key   By traversing these gates, you gain the ability to travel through time and space.

Films

 * The Force from the Star Wars universe. It's an energy field, it gives powers. It has a Chosen One (and may have caused the virgin birth of said Chosen One). It has a will of its own, but nobody fully understands it (and it might be impossible to do so). The Jedi and their evil counterparts the Sith, along with a variety of lesser groups from the Star Wars Expanded Universe, each have their own belief systems about the true nature of the Force, but out-of-universe it's generally presumed that the Jedi are closest to the truth.
 * Eywa in Avatar is a Genius Loci physically comprising the neural network between the various flora and fauna on Pandora, and comprising the memories of various creatures, but is sentient and can cause Gaia's Vengeance when required.
 * While its motives are unclear, in Excalibur a Force-like... force... is referred to as "The Dragon".

Religion

 * The Force from Star Wars is based on Taoism, which teaches that there is a universal force called (but not named) the Tao that flows through all things, passively guiding the universe along a natural course. By living a certain meditative lifestyle, one can become "like an uncarved block" and then allow the Tao to shape them.

Tabletop Games

 * The Warp from Warhammer 40 K would be a rare evil version. It is malevolent (though was not always this way). It has, in fact, many wills (thanks to its chaotic nature), as its wills can be given identities in the form of Chaos Gods. Just like the Force from Star Wars, it can give super powers.
 * The Draconic Prophecy in Eberron can be this. It's left deliberately vague so that the DM can give it whatever nature he wants, but what has been confirmed about it fits: It gives people powers (Through Dragonmarks), it's pervasive and covers the material plane (leaving marks on the landscape, construction, etc). It has a will and a purpose, but those are so complex and long terms that no being can fully understand it. Dragons spend their whole lives trying to figure it out, only ever achieving small glimpses of the Prophecy's nature.

Video Games

 * The Light from Kingdom Hearts. Everything and everyone in the multiverse is made of Light. Everything of the Darkness is twisted, broken, unformed, and un-whole, and thus angry and hungry. The Light sends visions and Keyblades to certain Chosen Ones to prepare and equip them to save the world and redeem what was lost to Darkness.
 * Apparently the Voodoo from Tales of Monkey Island is this, according to the Voodoo Lady. Of course, real Voodoo has nothing to do with this.
 * The Lifestream of Final Fantasy VII, used as a fuel by the Shinra Electric Power Company. In its solidified form it is the materia that allows the use of magic, and is the combined spirit of all living things of the Planet, and when you piss it off enough it releases a whole bunch of monsters to get rid of whatever is annoying it.
 * It was recently revealed that City of Heroes' myterious "Well of the Furies" is actually a Sentient Cosmic Force. To date, its exact goals are poorly-eludicated, but seem to involve trying to take control of its Chosen Many, the "Incarnates."