MinigunMinor Aperture Science employeesMinor Black Mesa employees
Minor HECU membersMinor Resistance membersMishaps in the Reactor Chamber
Missing InformationMistake of PythagorasMk 2 Grenade
Mobility GelsMoby FranckeMods
Molotov CocktailMonorail (disambiguation)Moon
Mortar SynthMr. Chubby BeakMr. Friendly
Mr. ValveMultiverseMuscle Car
NECA Gordon Freeman Action FigureNanobotNarbacular Drop
NeoTokyoNeurotoxin GeneratorNew Little Odessa
Newell (disambiguation)Newell (scientist)Nihilanth
Nolan NorthNova ProspektObsidian Conflict
OdellOdessa CubbageOperation Black Mesa (Opposing Force: Source)
Opposing Force 2Oracle TurretOrdinance Storage Facility (disambiguation)
Otis LaureyOutside ApertureOverwatch
Overwatch EliteOverwatch NexusOverwatch Sniper
Overwatch Sniper RifleOverwatch SoldierOverwatch Standard Issue Pulse Rifle
Overwatch VoiceOxygen BottlesPanther Eye
ParanoiaParticle StormParty Escort Bot
Peer ReviewPeer Review (Decay: Source)Penguin
Perpetual Testing InitiativePeter'sPetroleum Station
PheropodsPhysgunPipe Wrench
Pistol (disambiguation)Pit DronePit Worm
Pitchford (disambiguation)Poison HeadcrabPoison Zombie
PolyroboPortalPortal: First Slice
Portal: PreludePortal: Still AlivePortal: The Flash Version
Portal: The Flash Version MapPackPortal (disambiguation)Portal 2
Portal 2: Lab RatPortal 2 Achievements and TrophiesPortal 2 soundtrack
Portal 2 storylinePortal ARGPortal Storm
Portal soundtrackPortal storylinePotatoFoolsDay ARG
Powered Combat VestPowerup BottlesProject Borealis
Propulsion GelProsperoProtozoan
Pulse ShieldPulse weaponsR-4913 and X-8973
RPG (disambiguation)Race XRadio (disambiguation)
Radio TowerRail transportRandy Lundeen
Randy Pitchford
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