10 Awesome Video Game Villains That Only Appeared ONCE

Metroid Fusion opens with a mysterious parasite bonding with our heroine, Samus Aran. This merge creates an evil duplicate of the galactic bounty hunter called SA-X.

After that, the devious doppleganger hunts Samus for the rest of the playthrough. Since this Terminator-like villain can't be injured until the final battle, Samus has no choice but to run or hide every time her malevolent twin draws near. For this reason, it's no surprise why Metroid Fusion was praised for its focus on tension, atmosphere, and scaring players out of their freakin' mind.

Even though SA-X is arguably the creepiest villain in Metroid, she's never appeared again. This is a shame, especially since the franchise has repeatedly incorporated aspects of the character into the follow-ups.

In the Metroid Prime sequels, Samus faces another evil twin called Dark Samus, who appears at specific intervals, in a similar manner to SA-X. The EMMI robots from Metroid Dread blatantly steal SA-X's MO, since they are unkillable entities who constantly hunt Samus.

Since the developers behind Metroid keep creating enemies that are (ironically) clones of SA-X, why don't they just bring her back?