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The Zeta Metroid is the sixth natural stage of a Metroid's life cycle. They appear as enemies in Metroid II: Return of Samus and its remake Metroid: Samus Returns. They also have a minor appearance in the Restricted Lab of Metroid Fusion.

The Zeta Metroid possesses a very different structure from all prior forms, as it now resembles a theropod dinosaur. This stage is the beginning of the species' adult phase, and thus requires a lot of firepower to kill. Although the Zeta Metroid no longer flies in Metroid: Samus Returns, it has high agility and is capable of climbing any surface. The Omega Metroid is the next and final stage for all standard Metroids.

In Metroid II: Return of Samus, Samus Aran encounters three Zeta Metroids during her mission to SR388, while in Samus Returns there are four Zetas.


After an undetermined period of time, a Gamma Metroid's backside splits open and a Zeta Metroid emerges, shedding the previous form like a butterfly sprouting from its chrysalis. It has a slender body with four thin limbs which are equipped with a pair of claws on each end. The front of the head continues to feature a lamprey-like mouth, which can now produce fire and acid instead of lightning, while the back of the head is greatly elongated and reaches all the way to the middle of its spine when the Metroid is on a quadrupedal stance. A long thick tail is found at its rear. Other notable features are the eight red compound eyes, four on each side of the head. Unlike all prior forms, the Zeta Metroid is unable to fly and must move around on all fours. This posture protects the vulnerable membrane within its torso as it prevents Samus from easily targeting it, though the Metroid will occasionally stand on its hind legs to perform some attacks. In addition, the membrane's natural defenses have strenghtened, requiring more firepower to kill the creature.

Samus will encounter a rare, "evolved" variant of the Zeta Metroid that is characterized by a deeper shade of green and orange pigmentation on its body, along with a fifth pair of eyes. This Metroid is stronger than its standard variant, possessing higher defenses and capable of dealing greater damage to Samus.

Its original design differs immensely in Metroid II: Return of Samus. The Zeta Metroid's head, neck, limbs and torso are far shorter in length, all of which give the creature an almost infantile-like appearance despite being almost as large as Samus. In particular, its tail is extremely short and thin. These traits make the Metroid stand upright in a bipedal position at all times, leaving its membrane and the nucleus exposed to a direct line of fire. Contrary to its modern design, it is smaller than a Gamma Metroid and retains its ability to fly; in fact, it has great maneuverability in the air, moreso than its younger, slower forms. It is able to spit out large fireballs.[1]


The first Zeta Metroid in Samus Returns.

In Metroid II: Return of Samus, the Zeta Metroid perpetually floats in the air, occasionally making quick dives toward Samus and then coming to a halt in order to spit large fireballs. It is during this sudden stop that Samus can easily shoot Missiles at the Metroid's front. If she is skilled enough to outmaneuver the Zeta Metroid and get behind it, she can shoot at its back which multiplies the damage of each Missile nearly twofold. When first encountering the Zeta Metroid, it is seen emerging from the back of a Gamma Metroid, with the husk unceremoniously dropping offscreen. The Zeta can only be damaged from the front or the back; firing straight up from underneath does no damage. It requires 20 missiles to take down.

Metroid: Samus Returns has a drastically different battle sequence for Zeta Metroids. Instead of flying, they crawl along the ground as well as climb on the walls and ceiling. As they do so, they will attack with either a medium ranged flamethrower from their mouths, or spit long ranged green spheres of acid. Occasionally, a Zeta will charge up the latter projectile while on the ceiling and launch a barrage of six; these charged acidic projectiles will continuously bounce off of the room's surfaces and will not dissipate even if they hit Samus. Alternatively, it may instead charge its fire breath into an arcing-fireball attack. When the Zeta is using either of its ceiling attacks, Samus can use her Grapple Beam in a similar fashion to the Grapple Lasso, grabbing onto the Zeta Metroid's back and smashing it against the floor. The creatures can also lunge at her as a melee attack which she can parry with her Counter; the Zeta Metroid quickly recovers and attempts to pounce Samus, but she keeps the creature at bay while continuing to fire at its underbelly.

The Zeta in Samus Returns is also much more durable, and its backside is no longer a weakspot as the shell will cause missiles to harmlessly bounce off, with its weakness limited to its membrane and mouth. However, it can now be damaged by the Ice Beam or the Beam Burst.

Official data[]

Metroid II: Return of Samus Manual[]

"Multiple mutations will cause a Metroid to continue to grow into an even larger and more powerful adversary."

Nintendo Power issue 31[]

"The fire-breathing Zeta Metroids are equipped with armor on their lower bodies. You'll only hurt them from the side."

Virtual Console manual[]

Metroids (p. 16)
Zeta Metroid
"This Metroid has gone through its second molting. Its attacks are now even stronger."

Metroid: Samus Returns Official Guide[]

Zeta Metroid (p. 22)
"This is the fastest Metroid of the bunch, at least relative to its size. Zetas are lizard-like Metroids that spend a good portion of their time fighting from the walls and ceilings of their respective hiding rooms while they spit acid and fire at their prey. They're among the most cowardly of the Metroid family when it comes to fighting style—or maybe they're the craftiest, using their climbing and projectile-spitting abilities to their advantage. Either way, expect a fight with a Zeta to be on the short side compared to most other Metroid-type fights, but one that involves an awful lot of dodging and precision strikes."


  • The Zeta Metroids have a striking resemblance to the titular Xenomorphs from the Alien film series, and is perhaps another reference as the Metroid franchise is heavily inspired by the former. This similarity is further highlighted in Metroid: Samus Returns with its redesign (in particular its elongated head and its ability to climb on any surface), as well as the Zeta Metroid's debut where it drools over Samus, lowers its tail before dropping down and slowly lifting its head. This is a clear homage to the first appearance of a full grown Xenomorph in the first Alien movie.
  • In Return of Samus, the Zeta Metroid shares its battle theme with all other Metroids, save for the larvae and Queen. In Samus Returns, it has its own unique theme.
  • A flashback of Samus's battle with a Zeta Metroid in Metroid II appears in the Discover the Hunter Trailer for Metroid Dread.



  1. ^ Nintendo Power volume 31, pg. 57