The CryNet Nanosuit 2 (Crysis) is fully symbiotic with its wearer, fusing with them on a cellular level and enhancing their abilities to superhuman levels. It also is capable of evolving and adapting itself, continually growing more versatile.
The Doom Slayer (DOOM) wears the Praetor Suit, a powered armor forged in the depths of Hell that is capable of channeling Argent Energy to enhance his physical and combat abilities against the demons.
MJOLNIR Mark VI Armour (Halo) worn by the UNSC Spartan Supersoldiers...
...and the newer GEN 3 MJOLNIR armor.
Jak's Titan Suit (Jak II)
The Keyblade Armor (Kingdom Hearts) allows the user to survive in space, resist the corruption of darkness, and aids in combat.
Sora (Kingdom Hearts) wears mystically-enhanced clothing that allows him to assume powerful "Drive Forms".
The Tanooki Suit (Mario) one of Mario's many power suits.
Brick Baxter/Cyber Shadow's (The Young Guardians) prosthetic anatomy includes an immensely powerful exoskeleton.
Major Alexei Belitrov/SCP-2273 (SCP Foundation) is a Russian soldier from an alternate universe who has formed a symbiotic relationship with a biological exoskeleton created by "The Engineers" (SCP-1000) from the genetic material of houseflies.
Chaos/Imperial Space Marines (Warhammer 40,000) invariably wear power armour in one form or another.