Item sets are a feature introduced in the Mann-Conomy Update. Depending on the set, a cosmetic effect may be applied to the wearer when all the items are equipped. There are currently 72 item sets; the five Polycount Pack contest winners, three Australian Christmas sets, eight Über Update sets, Dr. Grordbort's Victory Pack set, the Swashbuckler's Swag set, nine Very Scary Halloween Special sets, three Australian Christmas 2011 sets, the hidden Eliminating The Impossible and Dual-Purpose Fruit sets, three Pyromania Update sets, the Grand Duchess set, eleven Scream Fortress 2013 sets, 11 Love & War Update sets, 10 Scream Fortress 2014 sets and the Sixties Sidekick set.
The Polycount Pack item sets require players to have the set's cosmetic item equipped to activate the item set bonus. All other sets, while they require their respective cosmetic items to complete them, do not bestow a set bonus. All set cosmetic items can be crafted using four Refined Metal and a weapon from the set the desired cosmetic item belongs to (for example, 4 Refined Metal and a Soda Popper would make a Bonk Boy).
Most item sets are designed around a central theme or strategy that relies on using the weapons in the set together. For example, the One Thousand and One Demoknights set for the Demoman is designed for pure melee combat, while the Airborne Armaments set for the Soldier rewards launching foes into the air by providing strong ways in which to finish them off before they land.
If a part of an item set is equipped, a list of items in the set as well as which are currently equipped appears when the item is inspected, either in the loadout menu or by other players. Unlike the others, the list for the Eliminating the Impossible and Dual-Purpose dkdjfjfkdkdmdmdksodjdjdjd,dkdmdkdkekskskskskendislelwpwpkwmekdmdkxmdmf,dockcmdmdkeoejemekwosospwpwoe,rmeksodjdmdkdkkdmxjdjdkrkekdk
- Added the "Grand Duchess" set.
- Set bonuses that alter stats, such as the ones the Special Delivery and Tank Buster sets granted, have been removed.
- Added the "Boston Bulldog", "Rocket Ranger", "Terracotta Trooper", "Burny the Pyrosaur", "Malice in Pyroland", "Murky Lurker", "Count Tavish", "Cursed Captain", "Doctor Galactic", "Sun King", and "Gravelpit Emperor" item sets.
- Added the "Retro Rebel", "Wicked Good Ninja", "Federal Express", "Ronin Roaster", "Fast Food Firestarter", "The Sons of Arsonry", "South of The Border", "Texas Tech-hand", "Builder's Basics Kit", "Straight Shooter", "Automatic Pilot" item sets.
- Added the "Rooftop Rebel", "Deep-Fried Dummy", "Sgt. Helsing", "Automated Abnormality", "Forgotten King", "Minsk Beast", "Templar", "Canis Ex Machina", "Reptiloid" and "Manngaroo" item sets.
- Added the "Sixties Sidekick" item set.