Skulls are easter eggs in Halo 3 designed to make the game more challenging or interesting.

Background

The skulls resemble those in the multi-player game variant "Oddball", and can be used as weapons in much the same way but they lack information text to pick them up. They are usually hidden out of the way, so one must search for them, or else know where they are, to get them.

Do note that in order to obtain any of the skulls, you have to begin the level from the beginning, on Normal or higher difficulty. In most cases, you do not have to finish the level after first picking up the skull, so can simply save and quit; nor do you need to carry the skull after picking it up. After you first pick the skull up, you merely need to press X at the level selection screen to select whether or not you want it, or any others, active.

"Gold Skulls" will grant you achievements when you first get them, but "Silver Skulls" will not. They are differentiated on the selection screen by their background, but are identical in-game. In the Campaign Scoring mode, activating gold skulls will grant you a multiplier to the points you receive, depending on the skull/s.

List of Gold Skulls

Iron

Level: Sierra 117[1]

Directions: This skull is at the end of the level. It is located on the roof of the building to the left of the building where Sergeant Johnson is being held captive (facing the entrance). You can get up by jumping onto the pipes. Go all the way to the end of the rooftop, and the skull will be there. *if you get on top of the building that johnsons on you can grenade jump onto the large horizontal pipes and then get on the walkway

Icon: A skull marked with a hammer.

Effect: If you die while playing solo, you will restart at the beginning of the level (you cannot revert to the last checkpoint at any time). If any player dies while playing co-operative, you will reset to the last checkpoint.

Point Multiplier: 3x

Black Eye

Level: Crow's Nest[1]

Directions: It's in the same room as you start in. Hanging down from the ceiling is a large pipe. Jump up onto this pipe, and on the end of it is the skull.

Icon: A skull marked with a smaller skull with a bruise under one eye.

Effect: Your personal energy shields no longer recharge normally. To do this you must melee an enemy with any weapon other than the Energy Sword.

Point Multiplier: 1.5x

Tough Luck

Level: Tsavo Highway[1]

Directions: At the point in the level when the Covenant Battle Cruiser flies overhead, there is a large pipe to your left following the road. Get up (there is a ladder), go to the yellow junction, and jump down to the left onto a support beam. Go to the end of this beam, and jump to the cliff to your left to find the skull.

Icon: A skull marked with three clovers.

Effect: Enemies dodge grenades, needles, and vehicle assaults with a far greater success rate.

Point Multiplier: 1.5x

Catch

Level: The Storm[1]

Directions: In the outdoor area with an AA Wraith, some Ghosts, and later a normal Wraith, there is a dome-like building to the end of the cliff. Get up onto it (using a vehicle and a grenade or an ally), and the skull will be there. Note that if either Wraiths are destroyed, the skull will disappear, and you will have to restart the mission.

My tip is to take out all the ghosts, and all of the TURRENTS in the wraiths. Then you need to get a warthog up against one of the walls, throw a FRAG grenade into it, and grenade jump up.

Note: DO NOT DESTROY THE WRATHS,(If you want this skull) the skull will disappear if a tank is destroyed!

Icon: A skull marked with a diamond.

Effect: AI controlled units throw more grenades, where applicable.

Point Multiplier: 1.5x

Fog

Level: Floodgate

Directions: After playing through the level for a short while, you will hear a marine yell “There! Over There!” If you look up to the right, you will see a single Flood combat form (holding the skull). Shoot it before it jumps away, and the skull will be launched, so it may take several tries to have it land on the ground. Shooting too early will leave the skull on the rooftop.

Icon: A skull marked with a swirl of fog.

Effect: Your motion sensor is no longer visible.

Point Multiplier: 1.5x

Famine

Level: The Ark[1]

Directions: Shortly before you reach the area where Johnson flies down and contacts Commander Miranda Keyes, you will notice a small fork, the other path leading to your future destination. Pass through here, and head to the end of the stretch with the platform overhead. At the end, turn right and you will see a boulder. Use it to climb onto the platform, and walk to the last of the supports going up. It has an opening over the slanting part of the platform, and the skull is in there. Use a grenade or deployable cover (Or your partner's shoulders if you're playing co-op) to get up. If you prefer, you can come back to here after getting the Scorpion and then get the skull.

Icon: A skull marked with a smaller skull.

Effect: All weapons that are dropped by enemies or are scripted to spawn on the ground (e.g., near a downed Pelican) have halved ammunition or charge.

Point Multiplier: 2x

Thunderstorm

Level: The Covenant[1]

Directions: After you get into a Hornet for the first time, fly to the first tower you see to your right (the one the Elites disabled). The skull is on the top of the ramp that overlooks the ocean.

Icon: A skull marked with a lightning bolt.

Effect: All enemies and Elite allies are promoted to their next available rank, where applicable.

Point Multiplier: 1.5x

Tilt

Level: Cortana[1]

Directions: The skull is at the top of the large circular room where Cortana asks your name, and says it’s very nice to meet you (your screen and movement don’t change for this one). To the left of the room will be some small, somewhat fungal, growths on the walls. Using these, jump up onto a platform. There will be some more nearby, so use those to get to a large circular platform with the skull on it. The skull will not be there after you retrieve Cortana.

Icon: A skull marked with a smaller skull with a hole in its head.

Effect: Enemy resistances are greatly increased. Where a particular type of weapon normally does slightly reduced damage (e.g., projectiles against Brute armor, or plasma against Brute flesh), it is instead greatly reduced.

Point Multiplier: 2x

Mythic

Level: Halo[1]

Directions: Hug the right wall from the very beginning of the level. Soon you will reach a cave with a dead end, and the skull is on the ground, among the rocks.

Icon: A skull marked with a circle with a smaller circle in it.

Effect: The health of all enemies doubles.

Point Multiplier: 2x

List of Silver Skulls

Blind

Level: Sierra 117[1]

Directions: After the first enemy encounter, head to the cliff (two Phantoms will drop troops off). To the right will be a rocky outcrop with the skull on it. It will be on a rock hanging off the edge of the cliff

Icon: A skull marked with an eye with a crossed out pupil. The skull's eye sockets are a blank white color.

Effect: Your HUD and weapon are no longer visible.

Cowbell

Level: The Ark[1]

Directions: In the middle of the area where you fight the Scarab there is a structure with portable gravity lifts and a Brute Chopper. Get one of the lifts. After defeating the Scarab, continue on until you pass the room with a lot of explosive plasma containers. In the hallway after this room, there is a tall section with openings above the turning point of the hall, and the skull is in the top one of these. Use the gravity lift to get there (place the lift around the middle of the ramp). If you don’t succeed, revert to your previous checkpoint and try again.

Icon: A skull marked with a cowbell.

Effect: The force of explosions is increased.

Grunt Birthday Party

Level: Crow's Nest[1]

Directions: After the encounter with a Drone swarm, you will soon reach an area with Drones coming out of pipes to the side. Head to the end of the tunnel, but don’t drop straight down. In the wall under you is a small room with the skull in it, so walk forwards off the edge then straight backwards to get inside. It is possible to walk off to the side of the tunnel and on to the gray part just below and then walk into the room. If you drop completely straight down on accident, don't fret; you can either revert or pick up a Grav Lift a head of time and deploy it.

Icon: A white skull marked with a candle.

Effect: If a Grunt is shot in the head, confetti explodes out of it (which can also cause damage) and children's cheer is heard in the background.

IWHBYD

Level: The Covenant

Directions: After the Arbiter kills the Prophet of Truth, walk to the end of the bridge with the Halo holograms and clear the Flood. "1" is the ring closest to the entrance, "4" is the damaged ring, and "7" is ring closest to Truth. Jump through the rings in the order: 4 6 5 4 5 3 4. If done correctly the rings should all flash, and the skull will appear on the small bridge leading to the platform with Truth’s body.

Note: In some cases you may need to complete the level after getting the skull to unlock it, unlike with the others. This is not always the case, however. After getting the skull check in the level selection lobby whether it is unlocked or not. If not, reload your last checkpoint, get the skull again, and finish the level.

Trivia: "IWHBYD" stands for "I Would Have Been Your Daddy", after a Sergeant Johnson quote from Halo: Combat Evolved.

Icon: A skull marked with a double helix.

Effect: Unlocks new, often humorous, dialogs for the AI.

Special Effects (Pictures)

Video

Gold Skulls Locations <youtube width="350" height="350>9WrXr4Aa3Bs</youtube>

Silver Skulls 3/4 Locations <youtube width="350" height="350>roXCIh2Rz60&NR</youtube>

Silver Skull IWHBYD Location <youtube width="350" height="350>LLOm7olquhk</youtube>

Guide to all 13 Halo 3 Skulls <youtube width="350" height="350">XIE7I2OPgyA</youtube>