The Tranquilizer is an alternative primary weapon for the Spy. It is a thin, sleek, silver handgun.
The Tranquilizer fires a fast-moving projectile dart that slows down enemies for a brief moment upon impact. Unlike the default Revolver, the Tranquilizer must be reloaded after every shot. Though the Tranquilizer's darts do not do much base damage, the slowdown effect from the dart makes the enemy much more vulnerable. Although the Tranquilizer's darts are projectiles, they cannot be deflected.
- The Tranquilizer was originally going to be included in Team Fortress 2.
- Briefly in development, it was possible to shoot every dart in your reserve ammo at the same time, instantly killing whoever you fired at.
- The dart model is actually a model from Team Fortress 2 that was unused for the Sydney Sleeper.