Might only be able to perform just a handful of feats.
May strain the user.
May require an incomprehensible amount of training and practice to achieve.
Daurgothoth (Forgotten Realms)
Ryu Hayabusa (Ninja Gaiden)
Rock Lee (Naruto)
Might Guy (Naruto)
Saiyans (Dragon Ball)
Namekians (Dragon Ball)
Cyborg (Teen Titans)
X (Mega Man X)
Asura (Asura's Wrath)
Galatea (Bubblegum Crisis Tokyo 2040)
Silver Surfer (Marvel)
Monkey D. Luffy (One Piece)
Roronoa Zoro (One Piece)
Sanji (One Piece)
Kryptonians (DC Comics)
Martians (DC Comics)
Kratos (God of War)
Dante (Devil May Cry)
Captain Atom (DC Comics)
Alex Mercer (Prototype)
Medaka Kurokami (Medaka Box)
Rex Salazar (Generator Rex)
Adam Warlock (Marvel)
Negi Springfield (Negima)
Minato and Minako/Hamuko Arisato (Persona 3)
Yu Narukami/Souji Seta (Persona 4)
Ajimu Najimi (Medaka Box); Via Big Out Fool (Martial Arts Skill)
Ryu Hayabusa (Ninja Gaiden) is well known for pushing his abilities beyond their limits.
As a saiyan, Goku (Dragon Ball) is capable exceeding his limits after every battle and even just through training only, as well a using the Kaio-Ken and Super Saiyan transformations to further increase his strength.
Namekians such as Piccolo (Dragon Ball) are capable of unlocking a higher consciouness from within to become Super Nameks and achieve great power.
As a kryptonian, Superman (DC Comics) Plus it's near a star, more increase his powers. In fact, if he have the right amount of solar energy, he can overcome any difficulties.
Hulk (Marvel) is famous just because he "gets angry, more becomes strong".
By eating three Rumble Balls, Chopper's (One Piece) Devil Fruit powers transcend itself, manifesting into a monster of immense power and no ration.