Mellows are purple, red, and green flying creatures similar to Mellas and Memus, that are found in Brinstar in the original NES Metroid game, its remake and Super Metroid. In the mentioned remake though, they can only be found in a limited area of Brinstar (about 5-6 rooms) and disappear for the rest of the game if Samus Aran destroys all of their nests (these nests/hives are only featured in Zero Mission), one of which is hidden behind a wall and guarding a Missile Tank. Mellows will defend their nests when a threat comes too close for comfort. Mellows spend most of their time circling their nest when near their nest or chasing foes when there is no Mellow Nest nearby.
Mellow hives go through three visible stages when damaged: healthy, where the nest is entirely intact; then becomes damaged and sags somewhat, the nest appears to be melting; eventually the nest sags even further, seeming to be entirely melted; finally the nest will degrade into the ground, melting completely.
"These creatures can pass through walls. They like to chase after you in groups."
"Travels in groups through rocks and walls. These weak creatures are defeated in one shot."
"Small and weak but pesky, they will swoop down at you diagonally."
- The creatures known as Mellas and Himellas are possibly related to Mellows, given their similarity in name, behavior and physiology.
- Artwork in the Japanese strategy guide for Metroid: Other M implies that Mellas and Himellas are subspecies of Reo. This would subsequently make Mellows a subspecies of Reo as well, although they are not featured in the game.
- The Mellow hives seen in Zero Mission bear a strong resemblance to the Fly Pods featured in Other M. It is unknown if they are the same structures or not.