List of unidentified species

A look at a crashed vessel from an unidentified species.

The following are a list of evidence and appearances of potential numerous alien species that have not been identified or named in the universe.

Overview

Milky Way

Forerunner indexing

According to a Catalog, before the firing of the Halo Array on 97,445 BCE, the Librarian studied and favored at least 123 species across three million worlds in regions the Forerunners explored in the Milky Way galaxy. The Catalog was uncertain however how many the Librarian aimed to preserve. While many sentient species were ultimately indexed and reintroduced, many of them did not reach Tier 7 of the Technological Achievement Tiers after the firing of the Halo array, where only a handful were encountered by Humanity in the Orion Arm of the galaxy, and not every species that were in the Covenant were cataloged by the United Nations Space Command, with even the Covenant client species keeping few records of their affairs with them.

Locations

Great dense cloud

Last communication

Right after the Halo array was fired, a final communication was heard by 343 Guilty Spark from a "great dense cloud". This was sent from a species that just managed to send out their communications out from their home system that was not encountered by the Forerunners or the Flood. Guilty Spark did not understand their message, but presumed it was hopeful signals. After the Halo array hit the cloud, the communication stopped.

Installation 04 (Alpha Halo)

Below is evidence of alien species arriving at the Halo installation Installation 04.

Crashed ship

Main article: Unidentified alien vessel

Around 40,000 BCE after the firing of the array, during an experiment 343 Guilty Spark conducted on the Halo, an Unidentified alien vessel crashed on the ring. However none of the species left the ship or attempted contact, and Guilty Spark built a sarcophagus around the vessel. Ultimately Guilty Spark was hopeful for the next species to arrive on the ring.

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  Unidentified ship.

Visitors to the ring

During the Battle of Installation 04, 343 Guilty Spark noted in logs made during the battle that the Covenant landing on the ring and seeking something was similar to other alien species who arrived at the ring who recorded what they saw and left. These visits ultimately lead to 343 Guilty Spark changing from being hopeful at meeting alien species, to threatening ships that went near the ring, this persisted until the UNSC Pillar of Autumn arrived.

Installation 05 (Delta Halo)

Below is evidence of alien species arriving at the Halo installation Installation 05.

Flood outbreak

It is suggested that there was potentially outside meddling that lead to a Flood breach at the containment facility, leading to an outbreak and eventual formation of a Gravemind on Installation 05.

Installation 07 (Zeta Halo)

Below is evidence of alien species at Halo installation Installation 07.

Banished occupation

During the Banished occupation of Installation 07, an alien called The Harbinger, and aliens known under Skimmers were present.

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  The Harbinger

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  Skimmer

System of Miasmic Giants

Below is evidence of alien species around the System of Miasmic Giants.

'Crecka's survival

Around 851 BCE, the Sangheili 'Crecka recalled a event that happened "many cycles ago" in the System of Miasmic Giants where a hostile species attacked a vessel he served on, where he was the last survivor, him escaping by piloting the ship randomly though slipspace. According to 'Crecka, the species did not speak a civilized tongue.

Line Installation 9-12

Below is evidence of alien species at Line Installation 9-12.

Crashed ships

The debris at this Line Installation, among others contains a number of ships belonging to species not known to Human or Covenant client species.

Netherop

Below is evidence of alien species on the planet of Netherop. The species was assumed extinct by John-117.

• In The Military Survey of Uninhabited Planets the Office of Naval Intelligence had a classified addendum that said Natherop was possibly abandoned, which meant that the original surveys might of found artificially constructed terrain features.

• Forgotten Highway: A stone highway that was not made by Humanity was present on the planet. It was cut into the cliff on what humanity called the Serpentine Canyon.

• Mountain runners: Oval-bodied ten-legged spider-like machines made by an unidentified species were used by marooned kids on the planet. It was not made with ferrous metal so a leg could not be attached to Frederic-104s magnetic mount. The machines had a driver and passenger compartment. Control of the vehicle was done with a control orb. The machine was not that much bigger than a M12 Warthog. The machines contained a coal-fired machine that charged batteries.

• Microwave-beam weapons: Marooned kids made use of weapons that looked like a sickle-shaped dish antenna. This weapon fired a microwave burst. These weapons were mounted on the mountain runners.

• Cave Cities: The unidentified species created "Cave Cities", before Lena, and her ancestors were marooned on Netherop, these were abandoned and had no food, but they did contain water.

• Tools: Several tools were buried on the planet, whenever one was unburied and figured out what it did. It didn't work.

Unknown Location

Below is a list of alien species in unidentified locations.

Solitary

On a world that was controlled by the Forerunners, there was numerous confinement platforms that were made to keep threats contained, one of these platforms had a security breach leading to the inhabitant escaping.

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  A broken "window" on the confinement platform.

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  The confinement platform.