The SA-X (named by Adam and presumably short for Samus Aran-X) was the main antagonist of Metroid Fusion and the eleventh boss Samus faces on the Biologic Space Laboratories research station. It is an X Parasite mimicking Samus Aran and her Power Suit.

Stick to the low ground and fire charged beam shots directly at the SA-X to destroy it. Your beam must be fully charged to damage it. As it approaches, Space Jump over the SA-X to the other side of the floor while charging your beam, and release the shot when you land.

Appearance. The SA-X is an exact copy of Samus Aran, or at least her suit. It's unknown what the SA-X really looks like underneath the armor, but it does have a rather creepy, expressionless, zombie-looking face with missing eye pupils. Its gender is also a mystery.

At first you won't be able to injure this huge creature with any weapon in your arsenal, even Ice Missiles won't have any effect. Instead, wait for the Omega Metroid to slash out and strike Samus deliberately, you'll then lose all your health except for 1 unit of energy.