Spy
The Spy is a suave backstabbing rogue that has the ability to insta-kill any class in the game with their knife. Spies are valued in that they can get important picks through the manipulation and deception of the enemy team. The Spy arguably has the worst direct combat ability, as it is solely designed to only get one or two kills at a time. As a pick class, the Spy will usually target the enemy Demoman, Heavy or Medic and either get the Medic to pop or drop his Übercharge. The Spy is also capable of incapacitating and destroying the Engineer's buildings.
6v6
Main Article: Spy (6v6)
In 6v6, the Spy is considered an offclass. It is most often run when one team has a disadvantage and they need to try and create an advantage (usually through dropping the enemy Medic's Über).
Highlander
Main Article: Spy (Highlander)
In Highlander, the Spy is often used to pick the enemy Medic, Heavy, Demoman, Sniper, and Engineer. Spies in Highlander must be aware that the enemy team has a full-time Pyro and is spychecking more often, leaving the Spy with less opportunities for picks.
The Spy is also the best scouting class in the game, providing invaluable information for his team. He can find how far along a Medic is to fully charging his ubercharge, where the enemy team is located, and in what direction they are moving towards in the safety provided by his watches.
Trickstabs
When spotted or confronted by an enemy, a spy is almost always put at a disadvantage, due to his low damage output. In times of need, Spies may use trickstabs to place themselves behinds the enemy. The are a multitude of ways to do so. While some are more useful/successful than others, each method can be used accordingly in different situations to get out of trouble.
Allowed Weapons
Template:Class Spy Primary Table
Template:Class Spy Secondary Table
Template:Class Spy Melee Table