The One

Yes, you read that right.

The One is an extradimensional entity from before time, in whom Order and Chaos exist in perfect harmony. It created Unicron (boo!), then cut him in half to make Primus (yay!). The Vok claim to be guardians of The One and followers of its will. They also seem to think that either it created the multiverse, or it is the multiverse. Details are fuzzy.

Fiction

3H comics

The Vok were the first known source of information about The One, whom they tended to describe themselves in relation to. [Note: Capitalization of Vok quotes is at editor's discretion; their lines were printed in all caps.]

We are the Vok. Guardians of The One. Defenders of the ultimate -- of that which must be. [...] For The One is power ultimate, and there are those who would divert its creation to their own ends. These enemies must be detected and destroyed -- wherever and whenever they appear.

The enemy in question at the time seemed to be the resurrected Tarantulas, who in fact had captured the power of two Vok and was preparing to wreak havoc upon prehistoric, post-Beast Wars Earth. The Vok sought to protect "the sleepers," by whom they meant the stasis-locked Autobots and Decepticons aboard the Ark. They believed this to be "the will of The One." Primeval Dawn Part 1

Later, they explained themselves again to their creation, Primal Prime:

We are the Vok, the guardians of The One. We are of the source, the core, forever committed to safeguard the plan. [...] We saw the entirety of the creator's vision. The One... and The All. A unity of worlds, timelines, and dimensions. A multiversal confluence, harmonized and organized. In perfect synchronicity.

That time, they seemed to be referring to The One as not the creator, but the creation. Notably, they never referred to Primus by name (nor Unicron, for that matter), though they did fear "the enemy of all creation," to whom Tarantulas was attempting to deliver the Matrix of Leadership. Primeval Dawn Part 3 As Tarantulas would later be seen inside Unicron during the Universe war, Unicron is likely that enemy. Escape This raises the question of how Primus fit into their cosmology, and in fact whether he was what they meant by the creator-One. Answers remain unclear.

DK Ultimate Guide

The One existed before time itself, witness to the birth of the universe. The One was curious about this new realm and created a new being, Unicron, to explore it. For some reason, The One then split its creation in two, one half still being Unicron while the other became Primus. In keeping with their creator's nature as a perfect balance of Order and Chaos, the twin "exploratory heralds" became the embodiments of those two principles, but separated. Transformers: The Ultimate Guide

Trivia

• The Armada cartoon, which came out between the 3H comics and the Ultimate Guide, provided an interesting parallel in its creation story. Narration in the series premiere declared, “Light years ago, deep in the cosmos, a unique, digital entity came into being. In search of other life forms, it sent explorers out to the furthest reaches of the galaxy. These digital, mechanical beings became known as Transformers." This was expanded upon in the novelization, which said that the Transformers' pre-war goal was to explore the universe, downloading their discoveries into Cybertron so the planet could grow in knowledge. Assuming the "digital entity" was Primus, then he seemed to be imitating his creator's own method of vicarious exploration.

• The One's method of creating Primus from the substance of Unicron mirrors Primus' creation of the Transformers, whose sparks are fragments of his own being. Abduction This process was explored in slightly more detail in the Simon Furman's apocryphal text story Alignment.

• The One's (and Primus', and the Liege Maximo's in Alignment, and to a lesser extent budding) method of splitting off portions of its lifeforce all have a strong correspondence with Emanationism, specifically the Gnostic flavor, wherein an all-powerful God known as "The One" responded to the unresolvable conflicts in the world by "emanating" polarized aspects of itself to fight them out until they achieved resolution, and then return to enlighten The One with their findings. (William Blake wrote a tiresome cycle of epic poetry about one such conflict.)
  
  
  From Teletraan I: The Transformers Wiki, a Wikia wiki.