In The Iliad, Diomedes goes on a god-stabbing rampage with the help of Athena. First he slashes Aphrodite when she tries to spirit away Aeneas. Feeling his oats, he attacks Apollo two times, but Apollo blinds Diomedes temporarily to save Aeneas (Aphrodite's demigod son). So essentially Apollo just throws a flash grenade at him, takes the guy, and runs. When Apollo and Aphrodite return to Olympus complaining about Diomedes, Ares descends on the battlefield on a mission. Athena leads Diomedes towards the god of war and guides his spear cast to take him directly in the gut. Ares screams and flees the field. Diomedes thus becomes the only mortal to wound two gods in a single day.
In Alcestis, Herakles (Hercules) visits Admetus, a man famous for his hospitality. Learning that Admetus just lost his wife, he decides to pay his host back by beating up Death, thereby bringing her back to life. Herakles' whole existence revolved around being physically strong enough to ignore physics and punch out whatever he damn well pleased.
Herakles also beat Ares in a straight-up fight (not that this is impressive, for being the god of war he's pretty much a sissy), and later on fought Apollo over a temple and managed to stand on even ground with him, and Herakles didn't have anyone backing him up for that fight. He also intimidated Charon into helping him and almost shot Helios out of the sky until the sun charioteer gave him a boat. This in addition to all the monsters he took out. It's not surprising though, he was pretty much bred to beat the hell out of things that other mortals couldn't.
The Northern Frog. The Nigh Invulnerable titular beast is speared through the mouth, chained down, then has its head bashed in with a rock. With the help of the invisibility-giving Ring of Solomon