Knife

The Knife is the standard close quarters combat (CQC) melee weapon in Call of Duty 4: Modern Warfare and one of the melee weapons in Call of Duty: World at War, Call of Duty: Modern Warfare 2 and Call of Duty: Black Ops.

Prior to Call of Duty 4: Modern Warfare, the knife was not a commonly used melee weapon in previous singleplayer Call of Duty games; it was available only in missions that feature stealth and/or reconnaissance. Before Call of Duty 4: Modern Warfare, the most common melee attack was the butt of the weapon. The knife is triggered by pressing the melee button (default V on the PC, clicking the right thumbstick on the Xbox 360, or clicking the R3 Button on the PS3), as taught in the "F.N.G." and "S.S.D.D." missions. However, on the Wii it is triggered by shaking the controller or by pressing down on the D-pad.

Singleplayer
The knife is the standard melee weapon for the player character in every installment of Call of Duty from Call of Duty 4: Modern Warfare onward. It is rarely seen used by NPCs, although they do have the ability to use a knife in Call of Duty: Modern Warfare 2. It will always be a one-hit kill on normal enemies, although it can take upwards of eighteen to nineteen knife hits to kill a Juggernaut.

Call of Duty 4: Modern Warfare
The knife will always kill an enemy in one slash or stab. In Old School multiplayer matches, however, two knife attacks are required to kill an enemy player at full health. This 2-hit-kill knifing also applies when double health is applied on Private Matches.

Call of Duty: World at War
The knife in Call of Duty: World at War is rather inconsistent in its ability to connect and kill enemies. It also makes a very loud and distinguishable swinging noise, often causing the user to be exposed, as it is highly unreliable. It is only consistent at a 1-2 foot range, where it usually guarantees a kill.

The Bayonet is an alternative to the knife, and can be attached on all Bolt-Action rifles, excluding the PTRS-41 (The PTRS is a semi-automatic, but is labelled in Create-A-Class as bolt-action). It also is attachable to the M1897 Trenchgun and the Type 99 LMG.

Nazi Zombies
In the Nazi Zombies map Der Riese the players can replace their usual knife with the Bowie knife that can kill zombies with one hit for the first 12-18 rounds.

Call of Duty: Modern Warfare 2
There are three knives available to the player in Modern Warfare 2:
 * The regular knife
 * The Tactical Knife, an attachment for Handguns which allows faster knife stab and faster recovery. USP .45's Akimbo attachment has the same swing speed as the Tactical Knife, but with the regular recovery speed.
 * The Throwing Knife, a ranged alternative, available as Equipment.

Also featured in Modern Warfare 2 is the perk Commando, which greatly increases the knifing lock on range, often resulting in large lunges which still kill players. Commando increases the knife's range to similar the length of the shipping crates on the Call of Duty 4 map Shipment.

The knife cooldown time can be shortened by quickly hitting the equipment button then switch weapons button. This is most effective when used with the Throwing Knife, and is impossible with Frags and the Blast Shield.

Call of Duty: Black Ops
There are currently two known knives featured in Black Ops:


 * The regular knife, although appears to be a Secondary Weapon.
 * The Ballistic Knife, similar to the Throwing Knife.

Trivia

 * In Call of Duty: Modern Warfare 2, NPCs now have the ability to use the knife, although it is extremely rare. Allied NPCs will usually throw enemy NPCs onto the floor and shoot them upon close contact instead of using the knife.
 * In Call of Duty 4: Modern Warfare, the only time an allied NPC, or any NPC, used a knife to kill an enemy was in "Ultimatum". When Bravo Team enters the first house, Price sees an enemy and silently kills him with a knife.
 * The first knife kill by an NPC is in Call of Duty: Modern Warfare 2's "Cliffhanger"; When Roach meets with Soap and enter the hangar, Soap sees an enemy, throws him towards the lockers, and down on the floor, before stabbing him with a knife.
 * There are three occasions in Call of Duty: Modern Warfare 2 where an enemy uses a knife in an attempt to kill the player. The first two occur in "The Only Easy Day...Was Yesterday" and "Just Like Old Times"; the player breaches the door and an enemy charges at him with a knife. The player would have to kill this enemy first before killing the rest in the room. Thirdly, Shepherd stabs Soap in the chest after knocking him down during "Endgame".
 * The only time an enemy uses a knife against the player in Call of Duty 3 is during one of the quick-time events, when getting ambushed in a building by a German soldier wielding one. The German repeatedly attempts to stab the player. The fight ends when the player manages to push the knife into his own chest, where he stares at it before falling dead.
 * In Call of Duty: Modern Warfare 2, when Soap goes to kill General Shepherd in "Endgame", he holds the knife in his right hand and nothing in his left while the player is able to attack by hitting the fire button, this is the first time in the whole of the Call of Duty series that the player holds a knife as a primary weapon.
 * In Call of Duty 4: Modern Warfare as well as Call of Duty: Black Ops, the knife model is based on that of the SOG Bowie knife.
 * All players seem to use the Knife with their left hand, this is most likely because all of the players use their right to shoot. However, this isn't the case in Call of Duty: Black Ops (Nintendo DS), as screen-shots show the player holding the knife in their right hand.
 * It is possible to get an assist with a knife by knifing an enemy player who is halfway through the transition into Last Stand then an ally finishing him off.
 * In the Nintendo DS version of Call of Duty: Black Ops, there is a screenshot which confirms that the player will use the balistic knife.