Octrolls were large, cephalopoidic organisms indigenous to SR388, which filled a niche similar to a Choot, although they were much larger and as such likely fed on a larger breed of game. Since they are actually capable of jumping much higher and able to deal more damage than their smaller counterparts, it might be that they in fact would have fed on Choots themselves. They apparently were particularly bound by location, however, and Samus Aran herself only encountered them in one particular location, leading many to believe they lived in small pockets sparsely peppered around the planet; either this or they were in fact critically endangered already by the time of Samus' arrival.
- When destroyed, they nearly always yield large energy units.
- They are encountered in only one section of SR388.
- Metroid II: Return of Samus (First appearance)