The Pfhor (pronounced "FOUR") are an extraterrestrial space-faring race of slavers that attacked the UESC Marathon in 2794. They seek to control the galaxy and perform numerous evil deeds in the games. The Pfhor were ultimately defeated in 2881, when the Pfhor system was sacked by the combined fleets of the UESC and S‘pht’kr. By the time Durandal returned to Earth 10,000 years after Marathon 2, they are a distant memory.
The Pfhor are bipedal, somewhat taller than humans, have three red eyes and grey skin. The arrangement of their eyes was changed from a triangle pointing down in Marathon to a triangle pointing up in the later games.
Little is revealed about Pfhor culture. They appear to have a rather complex bureaucracy, and according to Durandal their religion is "pathetically boring." The only information that has been gathered about their religion is the presence of Sfiera, a goddess of lightning and passion. The Pfhor have an empire, and specialize in slavery.
The separate types of soldier equipped within the Pfhor garrison are divided up into a caste system, each with its own armor and weapons:
- Fighter: Fighters are the first and most common enemies the player will encounter. All fighters wield a shock staff but the types of attacks they can perform are dependent upon their "color".
- Green and purple fighters can only use the staff as a melee weapon. Purple fighters have more health than green ones.
- Orange and blue ones are capable of melee as well as a ranged attack that fires energy bolts. These fighters have additional health. Blue fighters are faster and more aggressive.
- Black fighters are the strongest of all, being faster and more aggressive than the blue fighters, and stronger than the purple. They use both melee and ranged attacks, and are exclusive to Marathon Infinity.
- Trooper: Troopers are Pfhor soldiers that wear vacuum-enabled suits and carry a weapon similar to the player's assault rifle, which, unlike the player's weapon, never runs out of ammunition. Troopers come in three versions: Green (minor), Purple (major) and Blue-Gray (Super). Troopers in green suits are less aggressive than those in purple, and both versions can shoot grenades at the Player. Purple troopers will use grenades more frequently. Super Troopers are the strongest of all, and are exclusive to Marathon Infinity.
- Hunter: Hunters are heavily armored Pfhor who are able to withstand most projectiles, but possess a vulnerability to energy weapons such as the fusion pistol. They're equipped with a shoulder-mounted plasma cannon and howl when disturbed in Marathon, but do not do so in the sequels. Similar to Troopers, Hunter appear as two versions, Brown (minor) Hunters and Green (major) Hunters. In Marathon 2 and Marathon Infinity there is a third version of the Hunter that is blue (or gray in certain levels of Marathon Infinity), fires more projectiles, has more health, and is physically larger.
- Enforcer: Enforcers are tall and thin aliens that fire a unique weapon that the player can pick up if he kills one. In Marathon, this weapon acts like a more accurate version of the assault rifle, but in the sequels is more like a long-range flamethrower that can also fire symmetrically. When such a weapon is picked up, ammunition is random and there is no method of reloading. Also, when an Enforcer is killed with this weapon and the Flamethrower, the Enforcer's own weapon is destroyed in the process. Enforcers will only fire upon aliens unless disturbed by the player. Blue Enforcers are weaker than green ones. Alternately-colored Enforcers (yellow and silver) also appear in Marathon Infinity.
- Juggernaut: Juggernauts are essentially large flying tanks that attack the player with guided rockets and alien projectiles. Properly called Pfhor Assault Vehicles, Juggernauts are also known as "The Big Floaty Thing What [sic] Kicks Our Asses" by the Nebulons, a race of aliens mentioned in the game. Though a Juggernaut's rockets are not as powerful as human ones, they are the strongest enemy in the series. When a Juggernaut is killed it slowly descends to the ground, accompanied by the sound of a loud alarm. Upon reaching the ground it explodes in a bright white flash which is audible and visible from every part of a level. This explosion does massive damage to anything within its range. In Marathon, Juggernauts are all gray, rounded and organic looking, but in Marathon 2 and Marathon Infinity, their appearance more closely resembles tanks. In Marathon 2 and Marathon Infinity Juggernauts can also appear as an orange version that has more health and fires more often.
- High Pfhor: The Pfhor are divided into at least six "Ranks:"
- "Conditioned" - primarily reserved for slave races
- Most of the Pfhor encountered (with the exception of the Enforcer) are of the Aggregate Rank. However, Pfhor of higher castes are mentioned or speak to the player in the terminals. For example, Commander Tfear, who has supreme command of Pfhor Battle Group Seven, is of the Command caste.
The Pfhor have several servant races who fight with them, not by choice but because they are forced to do so.
- S'pht: The S'pht are the most commonly encountered slave race of the Pfhor. Also known as compilers, they have metallic heads, long red capes, and are equipped with an energy weapon under their capes. Depending on the class of S'pht, they can launch various sorts of glowing bolts which, in some cases, home in on the target. Although they appear tall, they actually use a floating machine to propel themselves. Without the Cloak and armor, they resemble a mammalian brain. They occasionally work with the Player and Durandal to fight the Pfhor.
- Hulk: Hulks are slow, massive, walking tanks the Pfhor use to fight. They have no ranged attack capability, but have been known to be able to send humans flying with their powerful blows. One example was by account of a survivor of a Pfhor attack, in which the Hulk in question "Picked Johnny up, and threw him against a pillar".
- Wasp: The Wasp is usually deployed in large groups, usually to annoy or confuse the target.  They are flying insectoid creatures which spit and move extremely fast. Lucky they lack armor and can be taken down in one or two pistol shots.
- Looker: The Looker is also believed to be a Pfhor slave race, it is a small insectoid creature with lumps on its back, when shot or when in range of the player, it explodes violently. It is weak and can be taken down in one pistol round, but is physically small and usually found in poorly lit areas. This can make Lookers hard to hit.
Pfhor of Note
- Admiral Tfear, the leader of Battle Group Seven, Western Arm, oldest serving admiral in the Pfhor Navy. Described as a brilliant strategist able to beat Durandal.
- Re'eer, a commander 5th class, studying the Pfhorish and Narsh languages and later potentially executed for stealing classified documents and feigning his own death or killed by the Humans.
- Rr'pt, a Pfhor commander loyal to Tycho, fighting against Captain R'chzne.
- R'chzne, a captain aboard the vessel seized by Tycho. Killed by Tycho.
- St'ngr, a science officer on Lh'owon, killed by the marine.
- W'rrl, a science officer on Lh'owon, presumably killed by the player.
List of Pfhor Ships
Pfhor are generally thinner and lighter than humans and are superbly adapted for low gravity environments. Durandal told me that there are many "clans" of Pfhor, each physically distinct from each other, but my summary only includes two of them. Only two clans of the Pfhor have been examined. The Fighter carries a shock staff, which is capable of attacking at different settings. The Trooper is armored for vacuum conditions and carries a combination explosive and impact projectile weapon which is similar to your AR-75. - Leela, from Marathon, Defend THIS!, Terminal 4
- The Pfhor having three eyes is a seven reference because
- Marathon - Level 3: Defend THIS!, first terminal
- Marathon - Level 0: Arrival, first terminal
- Marathon, Marathon 2: Durandal, Marathon Infinity
- Marathon 2: Durandal - Level 7: Ex Cathedra, first terminal
- Marathon - Level 3: Defend THIS!, fourth terminal
- Marathon - Level 7: Cool Fusion, second terminal
- Marathon 2: Durandal - Level 4: What About Bob?, third terminal, second message
- Marathon 2: Durandal - Level 26: Fatum Iustum Stultorum, first terminal