The Intruder is a fiery dragon-like creature which has made several appearances in the series and set the tradition of fire elemental creatures appearing as bosses, such as Phoenix and Volleone. It is also one of the few bosses in the series to get its own theme music, a piece called "Fire Dragon" which plays during its reappearance in the Gradius II's boss rush stage.
In the Japanese version of Life Force, the Intruder, like the stage it's in, has been recolored blue.
The Intruder will attempt to wrap himself around the player, occasionally breathing fire. In the original game, the Intruder's movements are fairly jerky and stiff, owing to limited programming of the era, but later games refined the programming to give it more fluid snakelike movement. In some games, the Intruder can physically crush the player with its body. Since it has relatively low health, however, this is somewhat unlikely.
In the NES version of Life Force, only its head ever appears. Here he has a very simplistic attack pattern, which consists of breathing fire in the player's general area. It moves its neck up and down to try and match the player's vertical position. Although its fireballs are quite large, the Intruder's health is very low and it will usually go down without being much of an issue.
It reappears in Gradius II, where it gains the ability of splitting into three at low health. This naturally greatly increases the difficulty of the boss, each head needing to be eliminated on their own.
The Intruder appears in the first episode of the Salamander anime series. Its appearance is constantly teased throughout the episode, as it's shown freely moving around the Salamander planet and activating the Sharp Cross traps on its narrow tunnels. It finally makes a proper appearance at the end of the episode, protecting the Zelos Force and serving as the final enemy the heroes face. It proves to be a very strong foe, being impervious to all weapons, so Eddie Evans pulls a heroic sacrifice to destroy it from the inside.
- There are smaller fire dragons that reside in other stars, suggesting several stages in the life cycle of this creature. These range from the smaller, weaker Fire Dragons that reside in small scale suns, to the multi-headed Vulture Dragon.
- Similar looking creatures are used as living weapons in the Core Warship Deltatry, perhaps even being the same species. These particular dragons turn on their master upon his defeat, suggesting cruel treatment.
- In Castlevania: Portrait of Ruin, a spell called "Salamander" summons an Intruder-like dragon that circles around its target, dealing massive fire damage.
- In the Yu-Gi-Oh! card game, there's a monster similar to the Intruder called Solar Flare Dragon.
- In Axelay, the Intruder makes a cameo appearance in the Stage 5 (the lava stage) of the game.
- In Gaiapolis, a 1993 arcade fantasy action role-playing game also by Konami, the player can summon an Intruder-like fire dragon for an ultimate attack.
- In Ninja Cop, an Intruder-styled dragon makes an appearance as a summoned entity in a boss fight.
- In Lightning Fighters, an Intruder-like special attack, called "Dragon Laser" can be used by the spaceship.
- In Gradius Gaiden, a boss, the Deltatry, which is based on the Trigon fighter, uses an attack which summons Intruder-like dragons.
|Gradius II: GOFER no Yabō|
|Stages (arcade)||Artificial Sun • Alien • Crystal • Volcano • Revenge of Moai • High Speed Maze • Boss Rush • Gofer Ship Interior|
|Port-exclusive stages||Volcano - Crystal (NES) • Enemy Base (NES) • Gofer's Lair (NES) • Temple (PC-E)|
|Bosses||Phoenix • Big Eye • Giga (NES) • Crystal Core • Death MK II • Jumping Moai • Big Moai • Desert Core (PC Engine) • Big Core MK II • Zub Rush • Big Core • Golem • Tetran • Gaw • Intruder • Zelos Force (NES) • Covered Core • Demos • Crab • Gofer|
|Ships||Vic Viper • Lord British • Alpinia|
|Stages||The River Styx • Fierce Blaze • Curse • Abyssal Forest • Speed Demon • Solar Assault|
|Bosses||Big Core MK I • Intruder • Tutankhamon • Dinosaur • Big Core MK II • Crab|
|Space entities||Nucleus • Intruder • Phoenix (Geezer Butler) • Goliath • Bubble Eye • Wyvern • Vulture Dragon • Blizzard Crawler • Yorogaton Chimera • Gillador • Volleone • Doom • Lynyrd Skynyrd • Triumph Kicks • Gaw • Giga • Killer Dwarf|
|Body horror||Abadon • Golem • Zylom • Big Eye • Gregol • Mad Skin • Brachion Eye • Biter • Berial • Huge Heart • Crawler (X) • Infected Statue|
|Plantlife||Choking Weed • Stinger Kid • Hunter Fang • Giga's Rose • Dendrodium • Hans Naughty|
|Episodes||Episode 1: Salamander • Episode 2: Paula's Meditation • Episode 3: Gofer's Ambition|
|Characters||Ike Lord British • Dan • Stephanie McBain • Eddie Evans • Doromo • Ministers • Lee McBain • Paula • Gofer|
|Enemies||Rugal • Sharp Cross • Golem • Giga • Zelos Force • Intruder • Tentacle • Big Core MK I • Moai • Xaerous Brain • Fire Dragon • Death Hand • Big Eye • Dee-01 • Phoenix • Amoeba • Nucleus|