A BOB, or "Born On Board", is someone who was born aboard the UESC Marathon. In the Marathon Trilogy, the only humans the player encounters are BoBs.


BoB sprite sheet from Marathon

BoBs are the crew members who live and work aboard the UESC Marathon and can be found in each Marathon game. BoBs have their own voice-lines which they will utter periodically in-game.

BoBs from Marathon are unarmed, while BoBs from Marathon 2: Durandal are equipped with .44 Magnum Pistols, and upgraded with Zeus Class Fusion Pistols in Marathon Infinity.

If the player is reckless when shooting and kills enough BOBs, they will consider him a traitor (often quite vocally) and return fire.


BoB sprite sheet from Marathon 2: Durandal

BOBs wear different-colored uniforms, but due to technical limitations, they all have the same face in-game. In Marathon, BoBs are unarmed and generally ignore the player, as well as occasionally announcing "They're everywhere!" These early BoBs are helpless and extremely prone to getting in the player's way. Also, in some of the levels on the Pfhor ship, they can be seen in pods, stuck in suspended animation.

Beginning with Durandal, BoBs carry weapons and fight with the player, on behest of Durandal. Marathon 2: Durandal BoBs carry the .44 Magnum Mega Class pistol, and are usually teleported out of an area once their primary objectives are completed. Lower-ranking BoBs drop pistol ammo when killed, while the higher ones drop their pistol.

Marathon Infinity introduced the "Vacuum Bobs" (or "VacBobs"), who wear vacuum-enabled armor and are armed with the Zeus Class Fusion Pistol. When killed they drop either fusion batteries or the fusion pistol, depending on rank. Throughout Marathon Infinity, BoBs are not always on the player's side, depending on the player' current allegiances. It is recommended to read each terminal as BoBs can be a dangerous foe.


Simulacrums from Marathon 2: Durandal

Simulacrums are Pfhor constructed imitation BoBs, or "assimilated BoBs". All simulacrums are unarmed and upon seeing the player's character they run directly towards him, usually shouting things like "I'm out of ammo!", "Thank God it's you!", or the infamous "Frog Blast the Vent Core!" When close enough (less than 3 meters [1]) they'll explode and inflict severe damage to anyone nearby. This is especially problematic on levels where a certain number of BoBs must be protected to succeed. Simulacrums exist in all three Marathon games and always wear green uniforms.

There are other differences between human Bobs and simulacrums: assimilated Bobs have red eyes, only two toes, no genitalia, and malformed teeth, but these differences do not visually appear in-game.[2]

Other notable differences:

  • Assimilated BoBs also run directly towards the player, whereas normal BoBs will move somewhat erratically and wander around.
  • Assimilated BoBs also never actually fire their weapons
  • Assimilated BoBs bleed yellow instead of red when shot.
  • All simulacrums wear green suits, which amusingly led to some of the real green-suit-wearing human BOBs on the UESC Marathon to take off their own clothes and run around the ship naked to avoid being mistaken for simulacrums.[3]


The color of the BoB uniforms represent the following classes:

BobprojectGREEN.pngGreen - Civilian Crew

Bobproject5555555.pngBlue - Civilian Science

BobprojectSALMON.pngRed - Civilian Security

Thvacbobproject-1.png Other - Vacuum BoB


The original crew of the Marathon consisted of 50 senior staff, 1150 officers and 24,000 civilians all of whom were citizens of the Mars colony or Earth. Some individuals were placed in stasis for the interstellar journey, but most civilians lived and worked on the ship and raised families there. As the crew aged, a new generation of humans were born and raised on the Marathon. By some, these children were looked down upon and called "Bob," short for born on board. These citizens grew to run the ship... It is your sworn duty as a security officer to protect Bob. - from Marathon manual

There were many humans in stasis on the Pfhor ship which the S'pht and I captured at Tau Ceti, destined for slavery in the Pfhor Empire. When I saw the colony was about to be destroyed, I did not restore them before we left. I also realized they might become useful. I have been reviving these colonists and asking for volunteers on the following terms: assist us and control your own destiny, refuse and face indefinite return to the unreliable Pfhor stasis chambers. Few are refusing. - Durandal, Marathon 2, What About Bob?, first terminal


  • Bungie has never made an effort to hide their feelings about BOB abuse:
    • The name of the M1 level, "Bob-B-Q."
    • Map text on M2 level We're Everywhere: "hey you, the bob carrying my 2nd pistol! - let's go!"
    • Map text on M2 level God Will Sort The Dead...: "Q: How do you tell the difference between the good Bobs and the bad ones? A: Good Bobs?"
    • The final piece of the "Vidmaster Oath" is " never, ever, leave a single Bob alive."
    • In Halo: Reach there is a class of the Covenant Elites known as a B.O.B. They appear with yellow Ranger class armor and a Blue visor. They are non-canon easter eggs, and have strong shields. Players get many points for killing them, and on, players are advised to "wipe them out."
  • In the fan Sequel Marathon Rubicon, there are new "AR Bobs", which are armed with Assault Rifles and wear similar armor to the Player.



  1. Marathon, Shake Before Using..., second terminal
  2. Marathon 2: Durandal, All Roads Lead To Sol..., second terminal
  3. We're Everywhere, first terminal, 2nd message