4. Thor
Thor possesses enough powers that he can destroy a whole planet. And if he does that then Hulk is not a big issue for him. There had been close fights with multiple occasions like in 2001 The Incredible Hulk annual edition, Thor electrified Bruce with a lightning bolt on his back, which made Hulk unconscious for a moment. And in the Avengers, the two is seen fighting with each other where Thor uses his hammer and gives him a strong thump.
