Nearly every weapon in the Marathon Trilogy requires some form of ammunition to fire. Each weapon has its own ammunition that is picked up by the player when approached or run over.
Description[]
This table lists all ammunition available in each game with regards to the weapon it can be used with.
| Weapon | Ammo | Capacity | Max | Notes |
|---|---|---|---|---|
| N/A | Fists | None | N/A | N/A |
 .44 Magnum Mega Class |
File:MagnumAmmo.png | 8 Bullets per Clip | 50 Clips | |
 MA-75 Assault Rifle |
File:MA-75BBulletAmmo.png | 52 Bullets per Clip | 15 Clips | Primary Fire |
MA-75 Assault Rifle/Grenade Launcher |
File:MA-75BGernadePack.png | 7 20mm Grenades per Pack | 7 Grenade Packs | Secondary Fire |
 Zeus Class Fusion Pistol |
File:FusionPistolBattery.png | 20 Energy Bolts per Fusion Battery | 30 Fusion Batteries | |
 SPNKR SSM Launcher |
File:SPNKRRocket.png | 2 Rockets per Pack | 4 Rocket Packs | |
 WSTE-M5 Combat Shotgun |
File:ShotgunShell.png | 1 Two-Round per Shotgun Shell | 80 Shotgun Shells | |
 TOZT-7 Backpack Napalm Unit |
File:TOZT-7FlameConister.png | 210 Flame bursts per Flame Conister | 3 Flame Conisters | |
 KKV-7 10mm SMG Flechette |
File:KKV-7Ammo.png | 32 Bullets per Clip | 8 Clips | |
 Alien Weapon |
N/A | N/A | N/A |
