- "These beings, these masters, they’re colonists. They overtake worlds, they just consume them and then they move on to the next. And they’ve been here before, as sort of a trial run. It was the dinosaurs, but the atmosphere wasn’t conducive, right? So they waited it out, and they waited it out. And now, you know, with the ozone, the pollution, the carbon monoxide, polluted waters…well we practically terraformed it for them. Cause now they’re coming back, and it’s perfect. See the first wave, that was just the hounds, categories I through IV, it was nothing! They’re sole purpose was to aim for the populated areas and take out the vermin, us! The second wave, that is the exterminators, and they will finish the job. And then, the new tenants will take possession."
- —Newton Geiszler
Precursors are a race of colonizing aliens from the Anteverse and the creators of the Kaiju. In 2013, they reopened a portal to Earth, originally established during the Triassic period, and used the Kaiju as weapons to wipe out humanity.
Precursors are spindly creatures who stand over twelve feet tall, and are capable of living for millions of years. Their appearance is akin to that of an aquatic insect. They have translucent wings and shell-like bodies that reveal their internal system. They have elongated, crest-like heads and protrusions that stem from their heels, and small, opal eyes that are reminiscent of the eyes of a shark.
Precursors operate on a type of clerical hierarchy that typifies the fashion and culture of pre-revolutionary nobility in France. Depending on their appearance and position in their society, Precursors are given the ranks of "Cardinal", "Bishop" and "Ambassador". Their ranks are reflected in the design of their wide and flat crowns.
Precursor civilization relies heavily on bio-mechanical implements. They live inside large towering formations that are part of the environment and they use cages to maintain the cloned Kaiju.
The Precursors tried to colonize Earth during the era of the dinosaurs, but the environment proved uninhabitable for them. Millions of years later, however, the gradual pollution of the Earth made conditions ideal for them to colonize the planet.
August 10, 2013, the Precursors created the Breach to send the Kaiju to destroy humanity. The Precursors' plan to colonize the Earth was to send Kaiju in waves. The first was the shortest period that lasted from the first Kaiju appearance in 2013 to 2014.
The second phase is long-term, an eight-year period that was essentially a standoff between the Precursors and Kaiju against mankind. The third and final phase began in 2024 and would end with an extinction event of the human race.
The Precursors' extinction event began with the Double Event, an occurrence that heralds the arrival of two Kaiju, Otachi and Leatherback, from the Anteverse through the Breach to Earth. K-Science officer Hermann Gottlieb predicted that the throat of the Breach is continually expanding to accommodate the Kaiju the larger they became.
When Newton Geiszler Drifts with the Kaiju's brain inside the K-Science Lab, he caught a glimpse of the Precursors' true intentions and their relationship as the creators of the Kaiju. In doing so, he revealed information to the Precursors that left the Defense Corps' Jaegers, Cherno Alpha and Crimson Typhoon vulnerable to the specific strengths of Otachi and Leatherback when the Kaiju attack the Port of Hong Kong.
The second Drift he initiated with the Baby Kaiju's brain prompted the Precursors to hasten their creation of Slattern. Beforehand, they sent Raiju and Scunner to guard the Breach from the approaching Jaegers, Gipsy Danger and Striker Eureka.
When Raleigh Becket abandons Gipsy Danger to destroy the Breach, three Precursors within the creation facility glimpse the Jaeger as it descends into their universe. They and the Kaiju were killed when Gipsy Danger self-destructs. The resulting explosion destroyed the Kaiju creation facility and collapsed the Breach.
- According to Guillermo del Toro, the Precursors' appearance is meant to reflect “alien madness”. These creatures are so otherworldly that looking into their eyes would be "terrifying".