Kihunter

They seem to be very trustworthy, seeing that they were put on guard to make sure none of their opponents dare tries and gets to Mother Brain. Sadly for them, they weren't the best of guards, and were defeated by the protagonist of the series, Samus Aran.

While it can be conclusive that many Kihunters are still alive, it is known that many of them, probably a majority, died when the planet Zebes was destroyed.