Prequel is, 90% of the time, hilarious takes on the Elder Scrolls world. Another 9% is watching the main character, Katia, fail rather spectacularly at everything she tries. The last 1% was a dream she had, wherein a monstrous king/spider/dragon appears, impales her best friend through the chest, then hunts her through her own dreamscape as she desperately drags herself away. When she finally rises to face him, he pins her abdomen to the wall.
Siegfried from Dominic Deegan has a bad habit of inflicting these on others when he loses his temper. Dominic's been on the receiving end of such a beating twice. Now that he's become a demon, Siegfried has eschewed physical beatings in favor of Mind Rape and Demonic Possession.
From Homestuck, Aradia attacks Vriska at the end of [S]: Make Her Pay and delivers the most merciless beating we've seen in the comic so far, leaving Vriska unconscious on the ground and covered in her own blood. In all fairness, Vriska murdered her previously, so it's not entirely unjustified.
Also, when Jake meets the young Troll Empress (alias "sea Hitler"), he fails to hear his friend telling him that she's an alternate timeline version of her, not to mention already dead. He decides to kill her before she grows up, pounces on her and attempts to punch*
either he forgot he had guns, or they didn't "follow" him to that Dream Land
her to death. He doesn't stop until another character knocks him out.
Big Bad Xykon from The Order of the Stick absolutely loves dishing these out when he's not busy torturing people. When Roy attempted to take him on alone, Xykon simply blasted him with a Meteor Swarm right in the face which led to Roy's death. In the PrequelStart of Darkness, he defeated Eugene's master by pretending to surrender, followed by beating the old man to death with his own award statuette.
And in these twostrips, Xykon utterly thrashes Spliced V. It starts with trap glyphs, Energy Drain, Maximized Energy Drain, another Meteor Swarm, and Superb Dispelling. Xykon finally ends it by hitting V with a chunk of the wall hard enough to cause V to lose his/her grip on the spliced souls. Then, he stops holding back, ending with him shoving his hands down V and O-Chul's throats, ready to Meteor Swarm their heads apart.
And don't forget the climactic fight of Start of Darkness.
In Shape Quest, Tonya (who is not a villain) finished off Lance in the Scarlet City tournament without him giving her too much of a scratch.
In the end of chapter one (and only) of Jesus Christ: In the name of the gun the title character took two pages to liquefy (sic) Hitler's (who happens to be a werewolf) skull. With a cross-shaped gravestone. Starting here.
Imperial Lieutenant Janek "Tank" Sunber, one of Luke Skywalker's childhood friends, has just helped capture a rebel base when he walks into an interrogation room to find two junior officers beating the hell out of a rebel prisoner. He immediately tells them off, only to hear the prisoner taunt him with Luke's destruction of the Death Star — with Luke's "betrayal" of the Empire and Tank. The other officers grin as Tank joins in the beating — then suddenly their grins are replaced by frowns, then looks of shock as they pull him off of the man to stop him from killing him with his bare hands.
Achewood has the Great Outdoor Fight arc... which ends with a No-Holds-Barred Beatdown of the event venue itself. (The term "full service beating" is used as well.)
The Inexplicable Adventures Of Bob:Galatea delivers one to Riboflavin,here. Her motivation is that Riboflavin had been delivering a similar beat-down to Bob, before she stepped in. Well, Golly had always said that, unlike her sister, she understands how her claws work.
