I've seen better sides of beef been run over by a combine.
— The Engineer on unappealing sets of items
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 thirty 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 and three Pyromania Update sets.
The Polycount Pack item sets require players to have the set headwear equipped to activate the item set bonus. All other sets, while they require their respective headwear and, if applicable, Miscellaneous item to complete them, do not bestow a set bonus. All set headwear and misc. items can be crafted using four Refined Metal and a weapon from the set the desired headwear/misc. that the 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 Fruit sets remain invisible until all items are worn together. If the entire set is equipped, any effects it provides are also listed.
List of item sets
September 30, 2010 Patch
- Added "The Special Delivery", "The Tank Buster", "The Gas Jockey's Gear", "The Croc-o-Style Kit", and "The Saharan Spy" item sets.
December 17, 2010 Patch (Australian Christmas)
- Added "The Medi-eval Medic", "The Hibernating Bear", and "The Expert's Ordnance" item sets.
February 14, 2011 Patch
- Fixed players getting set bonuses applied on tournament servers when the server is restricting the player's weapons using the item_whitelist.
- [Undocumented] Fixed players getting set bonuses applied on Medieval maps for items that are not allowed in medieval mode.
June 23, 2011 Patch (Über Update)
- Added "Black Market Business", "The Man of Honor", "Lawrence of Australia", "One Thousand and One Demoknights", "The #1 Fan", "The General's Formals", "The Airborne Armaments", and "The Clinical Trial" item sets.
July 20, 2011 Patch (Dr. Grordbort's Victory Pack Update)
- Added the "Dr. Grordbort's Victory Pack" item set.
October 13, 2011 Patch (Manniversary Update & Sale)
- Added the "Swashbuckler's Swag" item set.
October 27, 2011 Patch (Very Scary Halloween Special)
- Added "The Curse-A-Nature", "The Tin Soldier", "The Infernal Imp", "The Highland Hound", "The FrankenHeavy", "The Brundle Bundle", "The Mad Doktor", "The Camper Van Helsing" and "The Invisible Rogue" item sets.
November 2, 2011 Patch
- Added a taunt for the Tin Soldier set
November 22, 2011 Patch
- Added a taunt for the FrankenHeavy set
- Fixed set bonuses activating outside of the proper holiday for holiday restricted items
December 15, 2011 Patch (Australian Christmas 2011)
- Added "Santa's Little Accomplice", "Dr. Grordbort's Moonman Pack" and "Dr. Grordbort's Brainiac Pack" item sets.
March 8, 2012 Patch
- [Undocumented] Added the Eliminating The Impossible set.
May 3, 2012 Patch
- [Undocumented] Added the Dual-Purpose Fruit set.
June 27, 2012 Patch (Pyromania Update)
- Added "Public Enemy", "Dumpster Diver" and "Urban Professional" item sets
November 2, 2012 Patch
- Added the "Grand Duchess" set.
July 10, 2013 Patch
- Set bonuses that alter stats, such as the ones the Special Delivery and Tank Buster sets granted, have been removed.
October 29, 2013 Patch (Scream Fortress 2013)
- Added the "Boston Bulldog", "Rocket Ranger", "Terracotta Trooper", "Burny the Pyrosaur", "Malice in Wonderland", "Murky Lurker", "Count Tavish", "Cursed Captain", "Doctor Galactic", "Sun King", and "Gravelpit Emperor" item sets.