Omega Metroid

The Omega Metroid is the sixth and final stage of a typical Metroid's life cycle. An Omega Metroid is typically about twice the height of a human; its well-developed exoskeleton exposes only a small area of its softer membrane around its stomach. Like the previous Zeta stage, an Omega Metroid has a leech-like mouth, a bipedal structure, a tail, and four clawed limbs.

Samus Aran encountered several Omega Metroids during her mission to SR388. She would later fight another Omega Metroid created by Galactic Federation experiments on the Biologic Space Laboratories research station. It is never fully explained as to why the Omega Metroid appears in the Docking Bays while the BSL Space Station is being propelled towards SR388. However, it is likely that one larval Metroid escaped from the Restricted Laboratory before its destruction and quickly developed.

Samus was not initially powerful enough to defeat the Metroid. However, with the assistance of the SA-X and its Ice Beam ability, the Omega Metroid was defeated.

Metroid II
The Omega Metroids are quite a bit slower than their Zeta counterparts, but can deal an enormous amount of damage. They maintain the basic structure of their last forms, and at the same time keep the same weaknesses. Samus must shoot them either in the stomach or back, although a shot to the latter causes more damage.

Omega Metroids typically levitate around while periodically pausing for a moment. Samus can use the Screw Attack to counter a lunge attack from an Omega, and to preserve her health. Omegas also spit deadly acid in battle. Without utilizing their weakness, they require 40 missiles to bring down.

Samus Aran encountered four Omega Metroids during her mission to SR388.

Metroid Fusion
Samus only encounters one Omega Metroid on the BSL research station. This specimen is much more powerful than those encountered on SR388 and is able to reduce Samus' health to critical levels in one swipe. After discovering the Restricted Lab, Samus begins to find discarded membranes in Sector 1 which were likely left behind as the Omega Metroid rapidly metamorphosed from its larval form.

Samus enters the Docking Bays, hoping to make a swift escape from the Station. Instead of her ship, however, she finds a giant shell larger than the Baby lying amidst the wreckage of the Docking Bays. Samus begins to run back, but suddenly the Omega Metroid bursts through the wall. Samus shoots it in vain, but none of her current weapons even seem to damage it at all. The creature slashes her just once, throwing Samus to the other end of the room. As it moves in for the kill, the SA-X joins the fight. Ignoring Samus completely, the SA-X moves right up to the Omega and begins shooting the creature's chest with the Ice Beam, revealing the Omega's weak point to Samus. The SA-X is also hit by the Omega's claws, and the X form Samus had seen previously floats formlessly in the air. Samus uses up the last of her strength to leap into the X, restoring all her health and returning the Ice Beam to her. This scene is likely a recreation of the ending of Super Metroid, where Samus is saved from death by a former attacker and is given a powerful weapon to use against her enemy.

The Omega Metroid slowly creeps toward the left side of the docking bay throughout the duration of the battle in an attempt to swipe at Samus with its claws. To avoid this, Samus must use the Ice Beam to drive the creature backwards in a manner somewhat similar to the battle with Crocomire in Super Metroid. If the Metroid manages to connect with a claw swipe, Samus will be hurled to the end of the docking bay and knocked to her knees, exactly as she was at the beginning of the battle.

Ultimately, Samus succeeds in driving the creature back to the wall through which it came, and eventually the beast is destroyed. Samus's ship returns to the bay, allowing her to leave the station with moments to spare.

Inconsistencies
In Metroid II, the Omega Metroids are about 150% the size of Samus. In Fusion it is much larger. This is likely due to the screen size and resolution difference between the Game Boy and Game Boy Advance. In Metroid II, Omega Metroids are capable of levitation and plasma projectiles from their mouths, the latter which causes decent damage; they are also vulnerable against missiles only. In Fusion it does not demonstrate levitation or projectiles, its claw swipe can deplete entire Energy Tanks, their vulnerability against missiles is entirely non-existent, and while the Ice Beam proves effective against the Omega Metroid in Fusion, it had no effect in Metroid II. In the official artwork of all the Metroid stages, starting from the Alpha stage, all the Metroids have blue eyes, including the Omega Metroid and Queen Metroid. However, in Fusion the Omega Metroid has red eyes. Among these changes are also differences in color and design for the Omega Metroid, such as a golden maw, a fuchsia colored chest and abdomen, and larger claws.

Metroid II manual
"This mutation is absolutely huge; its power, incredible!"

Nintendo Power issue 31
"A fast and frenzied fight will ensue when you encounter this highly advanced creature. Be ready with Missiles."

Trivia

 * For unexplained reasons, the Omega Metroid attacked Samus despite the latter having Metroid DNA, whereas the other Metroids in the Restricted Area ignored her. This may be because the Metroids in the Restricted Area were preoccupied with the SA-X who admittedly was attacking them at the time. The Metroid which transformed into the Omega Metroid could also have possiby mistaken Samus for the SA-X, due to their similar appearance. The Omega Metroid may just be a generally violent creature and would have attacked anything that entered the Docking Bay. Finally, perhaps the Metroid saw Samus as competition, as there was no Queen Metroid aboard.
 * It's also possible that the SR388 Metroid forms have fully developed eyes, which is something that infant and larval Metroids don't possess at all. The Omega Metroid might have clearly seen Samus as being from an entirely different species despite having Metroid cells within her.
 * Interestingly enough, the Baby grew to an unnatural size and became the Big Metroid seen near the end of Super Metroid, similar to the Omega Metroid from Fusion. The fact that this Omega Metroid was created from the genetic material of the Baby may indicate a connection between their immense growth.
 * The Omega Metroid is the only fully organic boss in Metroid Fusion not infected by the X-Parasites (aside from the first stage of the Security Robot), but this is only due to its natural immunity to the X that it shares with others of its kind.
 * The battle with the Omega Metroid is the second boss battle in Fusion to feature a time limit. The first one was against the Human Core-X.


 * This particular Omega Metroid from Fusion is one of the few antagonists that succeeded in outmatching Samus. Mother Brain and Ridley in Super Metroid, Dark Samus in Metroid Prime 3: Corruption and an SA-X were all similarly capable of bringing Samus to the brink of death.
 * The Omega Metroid in Metroid Fusion drools some sort of substance after killing the SA-X. This may be the acid that others of its kind spat in Metroid II.
 * The Omega Metroid appears towards the end of the Metroid II commercial. It is the only enemy that is not a drawing in comic book style, though it first appears as one.
 * During the fight with the Omega Metroid in Fusion, Samus can be stunned by the Metroid's claws. The duration of this paralysis can be reduced by tapping up on the D-pad.
 * Oddly, the term "Omega" is usually used to describe the lowest-ranking member of a group, for example, in a pack of wolves.