Resident Evil 4 Cheat Codes for Gamecube

Snake in the Box
Sometimes when you destroy the wooden crates a snake will jump out and bite you. If you keep slashing with your knife when the box breaks you can kill the snake and receive a healing egg.
Submitted by: Jason

Special Costumes
After beating the game the first time, when starting a new game or playing a Round Two game, a new option appears that allows for Leon and Ashley to wear special costumes. Leon wears an R.P.D. uniform, Ashley wears pop sensation clothes, and Ada wears her black outfit from her mini-game.
Submitted by: Jason

More Money for Beerstein and Elegant Mask
When you find these items do not sell them right away. You can increase the value of the items with gems.
Submitted by: Jason

Ada Wong for use in The Mercenaries
Get a four-star rating in the Pueblo map of The Mercenaries

Albert Wesker for use in The Mercenaries
Get a four-star rating in the Waterworld map of The Mercenaries

Hunk for use in The Mercenaries
Get a four-star rating in the Island Commando Base map of The Mercenaries

Jack Krauser for use in The Mercenaries
Get a four-star rating in the Castle map of The Mercenaries

The Mercenaries Mini-Game
Complete the main game once

Alternate Title Screen
Complete the game once

Chicago Typewriter
Finish minigame assignment Ada

Professional" difficulty
Complete the main game once

Unlock Broken Butterfly Weapon
In the hall south of the hedge maze there is a locked door. Return to that area with Ashley, piggy back with her and she will unlock the door. This reveals the broken butterfly.

Unlock Matilda Weapon
Unlock the Matilda handgun (which fires 3 round bursts) by clearing the game.

Unlock Hand Cannon Weapon
Get the five star ranking on the mercenaries mini-game to unlock the Handcannon.

Unlock Chicago Typewriter Weapon
Beat Operation Ada, and the "Chicago Typewriter", a Thompson with 10.0 firepower, infinite ammo, no reload, and the fire rate of a maxed out TMP, becomes available at the merchant.
Submitted by: Peter

Unlock Rocket Launcher
In order to unlock the Rocket Launcher Special you beat the game on Normal and you get a chance too buy the Matilda and the Infinite Launcher. The Matilda is $70,000 and the Infinite Launcher is $1000000.

Unlock S.T.A.R.S. Uniform
To Unlock The S.T.A.R.S. Uniform You Must Complete The Game On Normal Or Hard Mode.
Submitted by: DJ

Unlimited Ammo Handcannon
Fully upgrade the Handcannon's firepower, reload, and capacity. The 'exclusive' option then raises the attack power to 99.9 and gives infinite ammo.

Looking at Ashley the wrong way
When Ashley is following you find something somewhat high off of the ground and climb on top. Then tell Ashley to stay put. Go below where you left Ashley standing. When you are underneath and you try to move the C-Stick up to look at Ashley, she will ask Leon what is he looking at and call him a pervert.

Killer7 Endorsement
Later in the game, the Merchant has a gun called "Killer7". This powerful magnum shares the name of an upcoming title by Capcom called "Killer 7".

Free Ammo
When you upgrade any weapon's capacity at a merchant, he will refill the magazine free of charge. This is very helpful with the magnum, or TMP

Get extra money and items
At various points throughout the game, you will come across different animals such as crows and fish. These animals can be shot and will reveal different items or amounts of money to obtain.
Submitted by: Yama

Hidden Trailers
If you don't push any buttons at the title screen. Then after about a minute or so a never-before-seen trailer will play. If you do the same thing at the title screen after the 1st trailer has played then the trailer from The Tokyo Game Show of 2004 will play. It will play these 2 trailers for as many of times as you don't push any buttons at the title screen.

Quick Aiming
There is a quick way to center your gun when aiming up or down. Simply tap the L1 button (takes out your knife) and you will quickly aim straight ahead.

Raise Max Health
If you mix: GREEN HERB + RED HERB + YELLOW HERB. It restores your health completely and raises your max health.

The First Shotgun
There are three main buildings in the village where you first see the chainsaw not-zombie. The shotgun is in the northeast building, on the second floor of the house.

Los Gigante
In Chapter 1-1, along the path towards the village you will run along a white dog trapped in a bear trap. If you help this dog he comes in handy later when you are fighting Los Gigante for the first time. About midway through the fight, you will hear the dog bark and he will come to your aid. Los Gigante becomes distracted, and begins to attack the dog rather than you.

Funny Character Animations
When Ashley is standing on a ledge and you are below her, look up at her and she will hold down her skirt and say something about you being a pervert and one or two other funny lines.

Double Broken Butterfly Ammo
If you buy the broken butterfly before you find it, you can hold twice the ammo. The shopkeeper will not sell you this gun if you already have it.

Lake Shooting
When you are at the lake before you face Del Lago (the thing in the water) stand on the dock right before the water and start firing into the water. The creature will not appreciate this.

Quick Side Turn
While holding R, tilt the C-Stick left or right, then quickly release and pull the R trigger again. You will turn almost instantly towards that direction.

Get Two Attacks on Saddler
When fighting Saddler, knock him down and stand near his eyeball head so that the "Knife" action appears. Shoot him instead and then start tapping "A" to do the action attack as well.

Big Money
In the Castle after you get out of the sewer you will appear at the top of a large ball room wear there are some monks doing a sacrifice. If you alert them they all run away but if you throw a grenade down every single person you kill will drop a spinel or a los illuminados pendent.

Green Or White?
Leon can't leave Ashley when he transitions into a new area (signified by the blurring effect); however, he can leave Ashley safe in the corner of a dangerous area then call her over when its safe. You can instantly tell if Leon is about to leave an area if the OPEN or context command is printed in green. If the command is printed in white, Leon will simply open the door to another section of the area. Use this to plan out where Leon can leave Ashley to brave the dangers ahead.

Chasing Ashley
The enemies who captures Ashley will seek to leave by the nearest area exit; these are the exits that have the "green" OPEN or context command as opposed to the normal "white" text. If they manage to reach one of these exits, then the game is over. When leaving Ashley to do stuff alone, be sure not to leave her near a green exit door.

Unlock Exclusive Upgrades
Once you have fully upgrades every stat for a specific weapon, you can purchase an expensive "Exclusive" upgrade for that weapon.
Note: Killer7 has no "Exclusive" Upgrade.

0.40 fire speed for Semi-auto rifle - completely upgrade Semi-auto rifle
1.8 firepower for TMP - completely upgrade TMP
10 firepower for Riot Gun - completely upgrade Riot Gun
100 max ammo for Matilda - completely upgrade Matilda
100 max ammo for Striker - completely upgrade Striker Shotgun
18 firepower for Rifle - completely upgrade Rifle
3.4 firepower - completely upgrade Blacktail
5 firepower for Red9 - completely upgrade Red9
50 firepower for Broken Butterfly - completely upgrade Broken Butterfly
Homing missle for Mine Thrower - completely upgrade Mine Thrower
increase chance for head shot by 5X - completely upgrade Handgun
Increase firepower for distant targets - completely upgrade Shotgun
Penetrate up to five bodies - completely upgrade Punisher