Captain Marvel
Abilities: Though she was born on Earth as a regular human, Carol Danvers absorbed the power of the Tesseract, which housed the Space Stone. She was granted superhuman strength, speed, and flight. She can emit extremely powerful photon blasters from her fists.
Additionally, she was made into a Kree-Human hybrid after the Kree soldier Yon-Rogg gave her blood transfusions. The Kree are naturally stronger and more durable than human beings. Thanks to her time with the Kree Starforce, Captain Marvel is also highly trained in combat.
Power scale: 100. "Captain Marvel, she is as powerful a character as we've ever put in a movie," Marvel Studios head Kevin Feige told Vulture. "Her powers are off the charts, and when she's introduced, she will be by far the strongest character we've ever had."
He was right. We saw Captain Marvel punch through an entire spaceship with complete ease, mere moments after realizing her true power. She didn't need training or time to learn how to harness her abilities, as many Avengers did.
We've seen her manipulate cosmic energy at will, armoring her own body with surging power that allows her to fly through space and withstand attacks: She flew across multiple light-years in one night while carrying an entire spaceship; she wasn't budged or even affected when Thanos punched her in the head. There is no one in the MCU who could even come close to her power.