He does deliver one to the not-Authority in What's So Funny About Truth, Justice, And The American Way? and he was still holding back.
Thor gives as good as he gets when it comes to Superman, and both beat the stuffing out of each other once, implying that they are about even.
Shortly after Superman gave one to Thor in the Avengers/JLA miniseries, the rest of the Avengers flip the heck out, and Superman is pounded into the ground by the Vision, Iron Man, She-Hulk, Wonder Man, and Hercules.
Mark (the titular Invincible) does this to supervillain Angstrom Levy and overestimates his durability, accidentally beating him to death.
Nolan almost killed him when the latter wouldn't go along with his world domination plans.
Sadly, the one implied by the cover of issue 50, Mark beating Cecil to death, doesn't happen.
Oliver, however, does just fine at beating the Mauler Twins to death.
Taken Up to Eleven in the Conquest "arc," which is actually four full issues of almost nothing besides Conquest smashing Mark into more and more bloody pulp. It ends with a Crowning Moment Of Awesome in which Mark, having lost the function of his arms and legs from the savage battle, manages to headbutt Conquest, caving his opponent's skull in.
Secret Six: Deadshot delivers multiple beatdowns of this sort to a gang of white supremacist thugs. The first one results in one of the thugs getting his eye put out, while subsequent beatdowns occur over one night when the thugs decide to go after him for revenge. The beatdowns just keep getting more and more humiliating until Deadshot's date finally offs them.
Pretty much every fight involving Superboy-Prime is this, though his first fight with Connor (regular Superboy) stands out in that he not only beats Connor to within an inch of his life, but he literally kicksKrypto halfway across Smallville. The JSA, Teen Titans, and the Doom Patrol arrive shortly after that. Does this change anything? Nope. Prime wipes the floor with them; he kills Pantha, Baby Wildebeest, and Bushido, and rips Risk's arm off. He was in the process of beating the snot out of Beast Boy when a bunch of Flashes arrived and managed to seal him in the Speed Force for a good deal of time (It didn't hold, obviously). The other one that stands out is the one against the Superman of Earth-Two. Prime beats him to death with his bare hands even though both are depowered. We get to see every single minute of this.
In "A Death in the Family," this happens to Jason Todd's Robin at the hands of the Joker in the third chapter, as Jason is beaten within an inch of his life with a crowbar. Batman later pays him in full in the Knightfall saga, roaring Jason's name the whole time.
And speaking of Knightfall, Bane finishing off an exhausted Batman by beating him to a pulp and then breaking his back. Bane later gets the crap beaten out of him by Azrael.
Bone has a male and female example when Thorn and Fone Bone get the tar beaten out of them before they're thrown into jail. Really hard to witness, especially when she discovers her bruises, black eyes, and a missing tooth. Then Fone smiles apologetically to reveal his missing tooth. Both are drawn like that for the rest of that day.
And each is missing a tooth from that point til after the big climactic battle.
Every now and then a new villain shows up or an old one with a vendetta and Spidey gets the crap beaten out of him. A lot of the time his My Name Is Inigo Montoya moment is very far away. If not for outside interference, he would've bitten the dust against Morlun, for instance.
In "Spider-Man: The Other" he does bite the dust against Morlun.
Spidey gives these out like candy if you push him far enough - say, if you're the Kingpin, and happen to have caused Aunt May's almost-fatal gunshot wound. Usually, he's sorry after, but after that one, he just kinda smiled.
After The Green Goblin kills Gwen Stacy, Spidey hunts him down and beats him within an inch of his life. Hell, if Spidey hadn't decided against it, Norman Osborn would've died that day. Though, Norman's glider did the job for him.
After a long globetrotting journey to burn out his own mind, Tony Stark finally faces off against Norman Osborn. The "battle" is completely one-sided in Osborn's favor since Tony is all but brain dead and in an outdated suit at that point. The beating is savage enough to render Tony comatose, which of course was All According to Plan. The beatdown was also broadcast on live television, winning Stark public sympathy and casting Osborn in a very negative light.
In the original Teenage Mutant Ninja Turtles comic series (Leonardo #1), the Foot manages one on Leonardo while he's out training solo. After a lengthy chase, he's cornered and numbers overwhelm him, though most of the actual beatdown takes place out of frame. By the time he's thrown through April's apartment window, Leo is only able to choke out that the Shredder has returned. For the next full issue (#10) he's unable to participate in the ensuing Foot vs. Turtles battle, and the next (#11) is dedicated solely to our heroes' recovery from the incident.
In The Punisher MAX storyline "Mother Russia", Nick Fury takes off his belt and whips the general who came up with the whole "Fake terrorists crashing a passenger jet full of innocent people as a distraction" plan. Over and over and over again. The guy is a bloody whimpering mess after Fury's through with him.
This is approximately one-half (or slightly more) of the standard MO of The Boys. The first half is usually some combination of surveillance, investigations, a little blackmail, messing with government agencies, etcetera, but sooner or later someone, somewhere, will be handed the kind of beating that, no matter how much the target might deserve it, is still likely to leave the reader feeling slightly queasy.
In an issue of The Avengers dealing with the Skrull-Kree war, The Vision displays a Not So Stoic reaction against an opponent after the Scarlet Witch is injured. An ally warns the Vision that he doesn't know what he's doing, and might beat the opponent to death. The Vision replies that he has a computer mind and knows precisely what's he's doing. "I am beating him to death."
In one of the later Ultimate Spider-Man story arcs, Norman Osborn fights off SHIELD agents while trying again to coerce Peter into helping him. When the conflict reaches its climax, a fight breaks out between Osborn in mutated form, a ship full of SHIELD agents, Spider-Man, and Harry Osborn in mutated form. When Harry tries to beat his father into submission, Norman goes insane with rage and smashes him to the floor, striking him in the face until he accidentally kills him. This shocks everyone into halting the fight, and a moment later Osborn shifts back into human form and requests that someone kill him.
This occurs in the Garth EnnisPunisher comic Streets of Laredo when a thug insults his boss' son. Rachel, the leader of a gunrunning outfit, has an openly gay son whom she adores. When one of her men calls him a "stinking queer" and proceeds to tell her that someone ought to put him down like an animal, she challenges the man, who is easily twice her size, to a fight. He has a Bowie knife and she has brass knuckles. He doesn't even scratch her and she completely wrecks him before delivering the final blow.
Preacher: Jesse does this to Jesus deSade, a child pornographer.
Wonder Woman delivered a notable one to Medusa after she petrified a child under Diana's protection. Medusa had to invoke Ares' protection to stop Wonder Woman from beating her to death there and then.
In Nextwave #6, Aaron gets one of these from Monica Rambeau, Elsa Bloodstone, and Tabitha for wearing a woman's bra and refusing to take it off. Played for Laughs.
Finally, in Nextwave #8, The Captain delivers one (offscreen) to Dread Rorkannu, which included doing something unpleasant to him with a toilet brush. We never get to know what (thankfully). Unsurprisingly, this too is Played for Laughs.
Anathos does this to the Legendaries right after reincarnating in Danael: as soon as he appears, he impales Jadina on his sword, slashes Gryf everywhere on his body, burns Shimy's eyes, and cut Razzia's arm off. All of this in two pages. While the comic had got quite dark at this point, this was so far the most violent scene in the whole series.
A strange one happens off-screen in issue 46 of W.I.T.C.H.. To convince Will to give up the Heart of Kandrakar, Phobos in Endarno's body mind-raped her. Will looked like she would give up... And whatever she did him, it reversed the body swap and left Phobos unable to walk and utterly terrified of Will. It's probable she would have tortured him to death if it wasn't for the need to send Phobos back in his body and recall Endarno into his own, and when the following issue gives her the chance the first thing she does is calling dibs on the killing shot ( Phobos was lucky: due the situation, Will opted to make it quick and disintegrated him).
In the first run on Infinity, Inc., Marcie Cooper, the third Harlequin, tricked Solomon Grundy into killing Sylvester Pemberton (Star-Spangled Kid I/Skyman) by using her illusion-casting goggles to appear as Jade, whom Grundy had become attached to. When Grundy realized he'd been tricked he mercilessly beat Marcie to within an inch of her life. In fact, the readers weren't sure if Grundy had killed her or not until Word of God clarified that Marcie wasn't dead since she hasn't appeared since.
In H'el on Earth, Superboy is pounded into the ground by Supergirl for trying to stop them from resurrecting Krypton. Having been severely weakened, he doesn't even bother fighting back and instead tries to reason with them.
X-23 delivers a brutal one to Zander Rice at the end of Innocence Lost. She could have easily killed him instantly with her claws, but after disabling his gun she put them away to beat the ever-loving shit out of him bare-handed in return for everything he'd done to her (short list: forcibly activating her Healing Factorat age seven with lethal doses of radiation, removing her claws at the same age one at a time to be coated in adamantium without anasthesia as part of his sick Revenge by Proxy against Wolverine, leaving her behind to be killed on a mission for no good reason, and thirteen years of general abuse and cruelty intended to strip her of her humanity). Her mother just gave her a mission to kill him. Laura pummeling him for about nine minutesnote Based on Laura's mission timer. Her fight with Rice begins at about 11:00 on the clock, and ends at about 01:00 straight? Payback.
The Doctor Who Magazine comic doesn't have that much graphic non-fantasy violence, but the No Holds Barred Beatdown Jodafra gives to his own niece Destrii in "Bad Blood" (after she stopped him from sacrificing a bunch of abducted children to an extradimensional monster in exchange for powers) is quite horrific. And pivotal in starting her Heel-Face Turn and making his irredeemability clear after he'd been introduced as a Lovable Rogue.
"Give your orders and ultimatums to those who choose to obey, or too cowardly to fight, NOT to me. Or learn again the difference between a God of Thunder and a mortal man in a metal suit."
In Injustice: Gods Among Us, the spinoff comic of the video game, Superman is a power-mad villain. In order to defeat him, Batman fights the Man of Steel to distract him long enough to scan a pill that grants normal humans super-strength and invulnerability. Superman beats the ever-living crap out of him, finishing the beatdown by breaking the Bat over his knee.
Immediately following this, the scan of the pill finishes. Alfred Pennyworth then takes the pill and, taking Superman completely by surprise, delivers the mother of all beatdowns on the Man of Steel. All the while he is yelling, “You don’t get to hurt my family anymore!” Needless to say, it’s Badass.