Gamma Metroids are Metroids which have grown past their Alpha Metroid form. They are followed by Zeta Metroids, Omega Metroids, and, if the Metroid has the proper genetic coding, Queen Metroids.
Samus encounters sixteen Gamma Metroids while on her mission to exterminate the Metroids on SR388. She can defeat them by firing ten Missiles at their head or back.
In Metroid Fusion, aboard the B.S.L research station, Samus finds a single Gamma Metroid in a stasis tank in the Restricted Laboratory of the Restricted Zone. Samus does not battle this Metroid, as it appears incapacitated. It is destroyed along with the rest of the Restricted Laboratory after an SA-X attacks Metroids in the area.
- ↑ "After molting from the lesser mutation, the Metroids will grow much larger, gaining the power to attack with lightning bolts." Metroid II: Return of Samus Instruction Booklet, Pg 31