I can't believe I just realized that no Metroid games feature a male final boss.
Metroid: Mother Brain (f)
Metroid Prime: Metroid Prime (nb)
Metroid Prime 2: Dark Samus (f)
Metroid Prime 3: A313 (nb)
Metroid II: Metroid Queen (f)
Super Metroid: Mother Brain redux (f)
Metroid Fusion: Omega Metroid (?/nb)
Metroid Other M: Metroid Queen redux (f)
...I guess the true final boss of Other M is Phantoon? but that's not part of the main storyline so I'm ignoring it.
