Metal Slug Wiki
Metal Slug Wiki

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The Big John is the fourth boss of Metal Slug 4.


The Big John is a giant mechanical puppet created by the Amadeus Syndicate.[1]This weaponized puppet was used by Amadeus Syndicate to transform the employees and attendees of a horror-themed amusement park into Mummies or Zombies, using a virus similar to what the purple gas and Monoeye UFO used respectively. The Big John is operated by a Rebel soldier.

It tries to turn the player into a zombie that, if successful, could end up being its undoing, as this opens up the possibility for the player to attack via the powerful "Vomit Laser".


The fight against Big John is composed of three phases:

  1. In the first phase, a wired metal claw is suspended at the top of the screen. It will move sideways until it stops right above the player. It will then descend its claw to smash the player or by shoot an electric laser downwards. The player can get on the claw when it strikes down for a few seconds until it retreats back up.
  2. After the metal claw is destroyed, the opening will periodically release a purple energy blast. Big John's mask breaks at this point. From the mouth of the actual face until the end of the battle, a Rebel soldier will periodically jump out to aid the Big John in its battle.
  3. In the third and final phase, Big John's eye sensors will turn blue, and its second hand appears from the right side of the screen. The second hand attacks by peroidically firing a TM-1L missile to the left side of the screen and deploying a large number of propelled virus bubbles that turn the players into zombies upon contact. Blue virus bubbles contain an item, which is either a Heavy Machine Gun, Rocket Launcher, Enemy Chaser, a mummy antidote or a first-aid kit. The missile can be destroyed with sufficient damage. Players can jump onto and walk on the missile without being killed.

Other Apperances

Metal Slug Defense

Introduced in version 1.26, Big John can be purchased as a unit for 300 medals. It costs 600 AP to deploy. Being a stationary unit, it is deployed using a Miner. It fires missiles its primary attack, and attacks close-range units by releasing virus vials; it summons its laser cannon from above as its special, and uses it to cover a relatively short area in front of it.

Its missiles deal high damage have very long detection range and infinite range once fired. This in combination with its fairly high health and the fast running speed of its builder make it one of the most effective units in the game. However, it cannot hit even low-flying air units with its missiles, leaving it largely defenseless against air units, which generally sit safely outside the range of its special. If inadequately defended, melee units - particularly Green Hazmat Soldiers and Smashers, which can deploy units behind/hover over the missiles - can shut it down by forcing it to rely on its weak close-range attack. Big John's builder is also vulnerable to penetrating shots from units like Big Shiee, which can give the opponent large amounts of AP while wasting your own.

Metal Slug Attack

The Big John appears for the "Zombie Parade" Extra Ops. Unit pieces can be earned through Another Story's "Halloween on a Moonless Night". New variants are also introduced.


Big John: The original giant mechanical puppet developed by Amadeus Syndicate.

Jade John: A variation of Big John developed for extremely harsh environments. Appears in Metal Slug Attack.

Real Jhon [sic]: Big John's true form. Its developers focused more on its abilities rather than appearance. Appears in Metal Slug Attack.


  • After exactly 15 shots at its face or destroying the claw, the Big John's mask breaks apart revealing the robotic frame.
  • The sound emitted by the propelled virus vials once it drops into the ground is recycled from the Big Snail. However, in Metal Slug Defense and Metal Slug Attack, Big John's bubbles have their own sound effects instead of Big Snail's death.
  • Like all Metal Slug 4 bosses, it was made using old sprites from previous Metal Slug games.



  1. Metal Slug Attack in-game description.
Metal Slug 4
Heroes Marco Rossi | Fio Germi | Trevor Spacey | Nadia Cassel
NPCs Tarma Roving | Eri Kasamoto | POW (Names) | Rumi Aikawa | Madoka Aikawa | Hyakutaro Ichimonji | President | Donald Morden | Allen O'Neil | Doctor | Rebel Army | Amadeus Syndicate | Shop Lady | Lumberjack | Bear | Haunted House Employees | Haunted House Attendees | Miners | Sailors
Enemies Rebel Infantry | Amadeus Infantry | Fanatics | Grenade Soldier | Bazooka Soldier | Shielded Soldier | Bikers | Rebel Rifleman | Mortar | Gatling Soldier | Hazmat Soldier | Pirates | Scientists | Sasquatch | Mummies | Dog Mummy | Chariot | Zombies | Tar Man | Supervisory Camera | Patrol Robot | Morden Robot | Amadeus Robot
Enemy Vehicles Di-Cokka | M-15A Bradley | T-2B Melty Honey | MV-280B | Nop-03 Sarubia | Girida-O | Turrets | Parachuetruck | 3-ton Utility Truck | R-Shobu | MH-6S Masknell | Flying Tara | Eaca-B | Hammer-Yang | Landseek
Bosses Brave Guerrier | Toschka Dalanue | The Iron | Big John | Sea Satan | Amadeus Mother Computer

Mecha Allen

Weapons Heavy Machine Gun | Rocket Launcher | Shotgun | Flame Shot | Enemy Chaser | Iron Lizard | Super Grenade | Drop Shot | Two Machine Guns | Grenade | Fire Bomb | Stone | Thunder Cloud
Slugs SV-001 | Slugnoid | Bradley | Metal Claw | Walking Machine | Forklift | Motorcycle | Landseek | Regular Army Helicopter
Missions "Let's Run Through!" | "Show Spirit" | "Snowy Road" | "Cadaverous" | "Go Ahead!" | "Secret Place"
Other Metallish System | Transformations | Items | Environmental Objects | RA-TTT | Hoist
Metal Slug Tetsuyuki | Hairbuster Riberts | Tani Oh | Shoe & Karn | Iron Nokana | Hi-Do

Mini-Bata | Allen O'Neil

Metal Slug 2/X The Keesi II / Iron Nokana MK II (X) | Aeshi Nero | Dragon Nosuke | Big Shiee | Hozmi | Rugname

Mosque Artillery | The Keesi II (X) | Karn (X) | Allen O'Neil | Dai-Manji

Metal Slug 3 Huge Hermit | Monoeye UFO | Jupiter King | Sol Dae Rokker | Rootmars

Twin Ohumein-Conga | Monoeyes | Hairbuster Riberts | Hi-Do | Rugname | Fake Rootmars | Clone Incubator

Metal Slug 4 Brave Guerrier | Toschka Dalanue | The Iron | Big John | Sea Satan | Amadeus Mother Computer

Mecha Allen O'Neil

Metal Slug 5 Metal Rear | Shooting Ray | Screamer | Sand Marine | Avatar of Evil

Black Hound | Stone Turtle (unused) | Gaia Elephant | Ptolemaios (unused)

Metal Slug 6 Bull Drill | Iron Sentinel | Brain Robot | Elder Centipede | Invader King

Invader Controller

Metal Slug 7/XX Worm Mecha | Crablops | Destroyed Crablops | Fall Mecha | The Union | Rebel Gigant | Kraken

Scrap Tower | Big Gate

Metal Slug: 1st Mission Rebel VTOL | Rebel Train | Macba | Rebel Zeppelin | Electromagnetic Crane | Weapons Port Boss | Hilde Garn

Facility Elevator | Macba | Rebel Truck

Metal Slug: 2nd Mission Big Bertha | Terrain Carrier | Rebel Reactor | Macba | Rebel Submarine | Tani Oh | Wired | Rebel Airplane | Hilde Garn's Slug | Rocket UFO

Power Generators | Rebel Rocket | Hyakutaro

Metal Slug Advance Formor | Emain Macha | Kaladgolg | The Keesi III | Cabracan

Allen Jr.

Metal Slug 3D Parachuetruck | Mosque Artillery | Spider-Bot | Underground Cruise Missile | Morden's Battleship | Morden's Castle | Allen O'Neil | Lugus | Lieu
Metal Slug Attack Pharaoh's Arc | Ptolemaios | Ball Slug | Great Mother | Mars Gigantalos | K-O3 Coupled Armored Vehicle | Land Blowfish | Cyclobster | Slug Square | Zoni Doloma | Quadro Jumper | Denturion | D-Gu | Fortmeranian | Rock Mole | Giant Copter | Et A Omnis | Vortex | Digger Base | Crusty Legs | Armored Crawler | Queen Big Snail | 7000 Class Locomotive | Riviere Hyll | Metal Fusioner No.223
Mobile games Rocket Control Room | Unknown Alien | Hellfire | Spiderbot | Cyclops | Mega Laser Turret | Mars Battle UFO | M-32 Water Carrier Plane | Kourai | Alien Floating Structure