May I Cut In?: Backstab an enemy and the Medic healing him within 10 seconds of each other.
On Her Majesty's Secret Surface: Start capping a capture point within a second of it becoming available.
Point Breaker: Kill 15 enemies who are standing on a control point they own.
Sap Auteur: Destroy 1000 Engineer buildings with sappers.
Sapsucker: Sap an enemy building, then backstab the Engineer who built it within 5 seconds.
Skullpluggery: Headshot 20 Snipers with the Ambassador.
Slash and Burn: Backstab an enemy, who then switches to Pyro before they respawn.
Sleeper Agent: Kill an enemy who triggered your feign death in the last 20 seconds.
Spies Like Us: While cloaked, bump into an enemy cloaked Spy.
Spymaster: Backstab 1000 enemies.
The Man from P.U.N.C.T.U.R.E.: Stab an enemy while fencing.
The Man with the Broken Guns: Backstab an Engineer, then sap 3 of his buildings within 10 seconds.
The Melbourne Supremacy: Dominate a Sniper.
Triplecrossed: Backstab 3 Snipers in a single life.
Wetwork: Stab an enemy to death while under the influence of Jarate.
Who’s Your Daddy?: Headshot 3 Scouts with the Ambassador.
You Only Shiv Thrice: Backstab 3 enemies within 10 seconds.
A Cut Above: Kill a gun-wielding Spy with your knife.
Agent Provocateur: Backstab your Steam Community friends 10 times.
Burn Notice: Survive 30 seconds after being ignited while cloaked.
Come in From the Cold: Get a Revenge kill with a backstab.
Constructus Interruptus: Kill an Engineer who is working on a sentry.
Counter Espionage: Backstab a disguised Spy.
Deep Undercover: While using the Cloak and Dagger, kill the same enemy 3 times, all within the same area in a single life.
Die Another Way: Kill a Sniper after your backstab breaks his Razorback.
Diplomacy: Kill 50 enemies with the Ambassador.
Dr. Nooooo: Backstab a Medic that is ready to deploy an ÜberCharge.
For Your Eyes Only: Provide an enemy with a freezecam shot of you flicking a cigarette onto their corpse.
FYI I am a Spy: Backstab a Medic who has healed you in the last 5 seconds.
High Value Target: Backstab an enemy who is dominating 3 or more of your teammates.
Identity Theft: Backstab the enemy that you're currently disguised as.
Insurance Fraud: Kill an enemy while you're being healed by an enemy Medic.
Is It Safe?: Backstab 50 enemies who are capturing control points.
Joint Operation: Sap an enemy sentry within 3 seconds of a teammate sapping another.