Pyonchi

Ponchi is the name of a small mammal kept by Samus as a pet in the metroid manga. The canonocity of the manga has yet to be determined and This is based upon the parts that have so far been translated.

Resembling a cross between a rabbit and a squirrel, he first encountered Samus, who was at the time only 3 years old, in the woods of Planetary Colony K-21 and snatched her backpack. He was eventually chased up a tree, where he refused to leave. Samus and "bird grampa" managed to get him down after the chozo suggested that she calm down and give it a name in order to see if it wanted to be friends, and thus Ponchi was "born".

After the space pirate attack, Samus brought along Ponchi with her to Zebes. Years have passed since then, and Ponchi still appears to be in good shape and has not yet shown signs of old age, so the lifespan of his species is of yet unknown. He usually stays around Samus out of years of trust, and both treat each other very well. Ponchi appears to have at least some sentience based upon his actions and wide range of emotions shown so far within the manga.