These are theories for some of the mysterious things in the Gradius Series.


  • Cores are made of psychic energy controlled by the final boss.
Evidence: Otomedius stated that the Core is the control interface and power source.
  • Cores are Bacterian embryos.
  • Cores are made of a unknown named glass-like and organic substance.
  • The reason Cores are not protected by heavy armor like the rest of the ship is that the armor the rest of the ship is made of is unusually impervious to heat. As such, some of the ship must be designed to allow heat through, and thus the "Core Barriers" are designated as a heat exhaust chute. This explains why some ships have more or less barriers, and some have multiple sets. The ships are likely using a variety of core with high heat output when they have more sets, for example. This also can explain why cores are not always left in "shielded" mode, the core produces heat and cannot remove it while the Shield is on.
  • Cores are energy amplifiers designed or mined by the bacterion, which are activated by a variety of energy unknown to humans. Thus, the bacterion can activate them by producing a simple, low power wave which engages the core, and then switching off of backup mode.
  • The Cores are living bio-mechanical ships with the cores as the nucleus.
Counter Argument- Some coreships are piloted by Wreekians.
  • It is also possible that the core is, quite simply, the cockpit, and thus its destruction shuts the entire thing down.
Evidence- Core Warships in Nemesis 90 Kai are piloted by Wreekians.
Counter Argument: Rexion Core regenerates it's core twice, by connecting to a large object. It would be unlikely for such a design to feature this. HOWEVER, it should be noted that cores look noticeably different in Gradius Generations/Galaxies/Advance, implying a different model or bacterion faction.
counter-counter argument: when rexion core was 'destroyed' the core may only of been slighly damage for pierced so the machine attached itself to Rexion core to reapair it instead of simply letting it die
  • when bacterion himself sheds some of his own cells they eventually form into cores (some bigger then others) the bigger ones form into core warship's while smaller ones form into the basic enemy. this explains why the enemys from most gradius games attack with extreme organisation and not just all at once because bacterion can controll the cores
  • The Core of any Core Warship is, in itself, a sort of ship. In Nemesis 90 Kai, the player can apparently 'enter' the Core of any defeated Core Warship ship before it is entirely destroyed; the interior shows itself to be full of machinery, including defense systems (the enemies you fight inside), unseen control systems (that can be piloted manually by, say, a Wreekian or a Bacterian), and a power source (the orb you reach at the end). The power source often contains data regarding the ship and it's functions, which is why the player can absorb its energy to obtain a new weapon. Larger and more complex Core Warships require more power and thusly, more cores.
    • As for the Big Core Custom, it possible that it is piloted by an unknown character that is apparently defecting from the Lars Empire. Why this is remains unknown.
    • Beacon, an example of a multi-Core Warship, actually throw cores at the player. This could be because Beacon was, or still is, a ship made to deploy cores onto other ships. Considering that the Bacterion are a multiplying race, it makes sense when you realize the potential for Bacterion pilots is likely rather excess.
    • Certain cores, like those on some Gunwalls, are shown flying in from behind the player. Such cores are also larger than the typical kind. Perhaps larger cores are capable of flying of their own accord, and can be simply installed into a Gunwall.

Bacterian Empire

  • The Bacterian Empire is composed of Brain-like creatures are beginning to evolve to humanoids like the Gofer Sisters.
  • The Bacterian Empire is made of cells that are born inside crystals from Planet Bacterian. When their crystal shells break, the cells get out and multiply to form various creatures and ships. These cells can also turn back into their crystal form.
  • The Bacterian Empire (and the Bacterians themselves) are exactly what they sound like: Bacteriums, heavily evolved into larger, more intelligent forms. The head of the Bacterian Empire, however, is the real intelligent one, while the others are lesser, more simplistic beings that simply conform to the leader's commands. The many different ships and fortresses are made from the smarts of the leader and the workforce of the 'minions', per se.

Xaerous Brain

  • Xaerous Brain possibly belonged to someone named Xaerous
  • Xaerous Brain is every single final boss of the canon Gradius series evolved in an different form


  • Bacterion is a evolved form of the Brain in Gradius 1.
Evidence: Bacterion stated in Gradius III that he will always be reborn. Some official sources states that the Brain in Gradius 1 is Bacterion.
  • Bacterion was created by mankind.
Evidence: Bacterion stated in Gradius III that he was born from the greediness of mankind.
  • it sounds crazy (and highly unlikely) but this IS the theories section so here is MY theorie. bacterion might be an evolved form of gofer, and gofer is an evolved form of the brain in gradius I. and the brain came from dr Venom during the northern cross war to help increase the size of his fleet, however dint evolve fast enough to create ships and so when dr venom left, he also left the brain. the brain then created itself a war ship to attack gradius (planet) (gradius I) then when the brain died in gradius I, one of its pieces went somewhere and eventually evolved into a brain and then into gofer. when gofer was killed one of his pieces went somewhere and somehow evolved into the brain then gofer and then into bacterion himself causing the next war (gradius III) when bacterion was killed a piece of him went somewhere to evolve into gofer to attack again (gradius IV) then when gofer dies again 3 of his pieces (one being bigger then the others) went off and evovled into brains which formed a warship to attack gradius (gradius V)
    evidence: the brain ( gradius I) gofer and bacterion all look like they have the same brain. this means its possible that the electric things keeping the brain in place may of been trying to simulate what its future (gofer) self as well as possibly for dr venom to send messages to it. also the brain may evolve because its simply trying to create a outer shell to help protect it from the outside world.
  • Bacterion is a recurring entity that somehow obtained a massive amount of human intelligence. This higher amount of thought perhaps led him to belive he was superior to every other creature in existence (hence, why he claimed to be born from 'the greediness of mankind' in Gradius III, as this more evolved form had realized his own power). This is also why many different Bacterion entities take on the form of a human brain: because they all contain human intelligence. In Gradius V, though, the entity shown is less resembling a human brain, and is the only brain to actually talk, claiming itself to be a fragment of Venom. If this is true, the brain we see is a Wreek brain, and its uncanny ability to talk (perhaps telepathically) is an example of Venom's Wreekian powers.


  • O.V.U.M. is a renegade Bacterian.
  • O.V.U.M. is just another name for Bacterion. After Bacterion was destroyed in Gradius III, pieces of him went to other places including the Dark Nebula. The piece in Dark Nebula had just became sentient and began to multiply, making an armada an cells and ships, which explains why the invaders from the Dark Nebula are similar to the Bacterian amoeboids. When the Vic Viper came to face him again, Bacterion used images from his Salamander forces to scare the pilot. Unfortunately, Bacterion strained himself and disintegrated into an orb and was finished off by Vic Viper.
  • O.V.U.M was formed by a mixture of brain cells from defeated enemies.
  • O.V.U.M is a rejected Bacterian experiment
  • O.V.U.M is a revived Zelos Force.
Evidence: Zelos resembles an ovum cell. Ovum cell, as in O.V.U.M.
The Face of O.V.U.M.

The appearance of O.V.U.M ripped from the game. Note the brain-like object in the center.

  • O.V.U.M. is the Original Visions of the Ultimate Monsters. Literally, O.V.U.M. is nothing more than a set of monsterous illusions generated by an otherwise defenseless, unseen Bacterion entity (possibly a fragment of Zelos or the Salamander forces, seeing as the bosses generated are from Salamander). This power is possibly from the unusual, possibly supernatural nature of the Dark Nebula, and the Bacterian that inherited it is the source of the voices and images that appear during the battle. Unfortunately, it was only able to use this power for a short time before being overwhemed by it.


  • Gofer was a Bacterian.
Evidence: A official source states that Gofer used to have a human form until he was transformed into a hive mind of a carrier.
  • Gofer was a human mutated by Bacterion.
Evidence: A official source states that Gofer used to have a human form until he was transformed into a hive mind of a carrier.

• In the aftermath of Gradius IV, Gofer's brain is split while other fragments head out into the cosmos. The halves become L.B. and R.B., the Gofer Sisters, and seek out remnants of Bacterion which would eventually become Dark Force. They invade the Solar System and attack Earth preceding the events of Gradius V, necessitating "G" to come to Earth and integrate with the planet, establish their technological reach to it as a new ally. While considered a side event from the main games, this allows for the Otomedius games to be part of the chronology, significant enough to be at least worthy of a mention.

Venom (Brain)

  • Venom was born from Gofer
  • Venom was born from Bacterion.
  • Venom was born from the Brain in Gradius 1.
  • Venom was Dr.Venom who was assimilated to the Bacterion Empire.
  • Somehow, a fragment of Dr. Venom's intelligence was assimilated by a Bacterian, and eventually grew into a Bacterion entity.

Lars Empire

  • The Lars Empire is a reincarnated Bacterion Empire.
  • The Lars Empire are humans infected by some sort of Bacterion parasite, presumably a smaller version of one of the common ameoboid entities. The entity may of affected their carriers mind, teaching them the ways of the Bacterions.
  • The Lars Empire are humans who learned to use Bacterion technology.


  • Moai are servants of Bacterion
  • Moai are created by Bacterion
  • Moai are evolved organisms formed on rocks which explains why the Moai are mostly found on rock. it also explains why they are in a lot of the gradius games, because they may spawn on the rock found througout the gradius galaxy
  • Moai were once guardians for civilizations before being absorbed by the Bacterian Empire. The Moai that players fight in the Gradius serius are reproductions from the knowledge of the cultures that used them, assimilated and reused by the Bacterian Empire.
Evidence: The Salamander anime has Moai used by the old civilizations of the planets Latis and Salamander, which emit electromagnetic signals that apparently repel the Bacterian hivemind.

Otomedius in Canon?

  • In the aftermath of Gradius IV, Gofer's brain is split while other fragments head out into the cosmos. The halves become L.B. and R.B., the Gofer Sisters, and seek out remnants of Bacterion.
  • After the events of Gradius Galaxies, the Gofer Sisters take up Bacterion's remnants, and from this, Dark Force eventually comes into being and starts to grow, amass power.
  • Centuries later, the Gofer Sisters invade the Solar System and attack Earth preceding the events of Gradius V, necessitating "G" to come to Earth and integrate with the planet, establish their technological reach to it as a new ally.
  • Erul Tron's family may be descended from the Burtons and the older brother could have had an interest in locating the antique Vixen; this could explain his disappearance and for Erul seeking to find him by coming to Earth for any information.
  • The counterattack against the Gofer Sisters appears to conclude at about the same time as the Fifth Bacterian War. In the aftermath, it's possible that while heading back to the proper point in time, the pilot of the Vic Viper T-301 sees and acknowledges Aoba Anoa in hyperspace before leaving, seeing as her ending shows the ship.
  • Since Dr. Venom was cut from the first Otomedius and appears in Otomedius Excellent, it is highly likely that the period of peace in between the games is when he once again attains a physical form; however, according to the dialogue of Stages 5 and 8 in Excellent, he seems to be either in the employ of "G" or has been given asylum by them.
  • When Dark Force has her growth stunted and is eventually destroyed, the Gofer Sisters retreat into deep space. It is assumed they will either return to the whole form of Gofer or will jointly act as the ultimate target for what will be the final offensive in Gradian Year 8100 (Earth Year 2100) that ends the Bacterian Empire. For now, we can only speculate that this is what Gradius VI will cover, if said game ever comes to pass.