Since Wolverine’s history began with his first appearance in 1974's The Incredible Hulk #180, he's clashed with Marvel's Green Goliath plenty of times, but his most vicious battle was actually with Banner’s wife Betty Ross, the Ultimate Universe's She-Hulk. In this alternate Marvel Universe, Wolverine’s assignment to track and kill the elusive Hulk takes a turn when Betty involves herself in an unorthodox manner. While Hulk and Wolverine's clash is famous for Logan being torn in two, it's in his battle with Betty that Logan displays real calculated cruelty.
Following the US government's attempted execution of the Hulk, Nick Fury discovers a series of unusual incidents that suggest Bruce Banner survived and is on the loose. Fearing the public reaction if this is discovered, Nick taps his old ally Wolverine to track and kill Bruce, despite the objections of his ex-girlfriend, SHIELD’s public relations director Betty Ross. In fact, Betty’s concern for Bruce has her take an illegally modified Hulk serum, manifesting superhuman strength while leaving her personality intact. The new She-Hulk drops into Tibet, interrupting Hulk and Wolverine’s battle, which is eventually concluded when Fury drops a nuclear bomb on them. Nick later interrogates Logan’s severed head about the events that preceded the bomb, and it’s revealed Betty and Bruce likely escape the blast. Fury imprisons Wolverine for his failure, though Logan is able to escape thanks to fellow mutant prisoner Forge.
In Ultimate Hulk vs. Wolverine #6 - by Damon Lindelof, Leinil Francis Yu and Dave McCaig - Logan ambushes Betty in a hotel room, pointing out a high-tech collar and saying, "Put it on... Or I'll kill your boyfriend." The collar is designed to resist gamma transformation, effectively staying the same size as its wearer transforms, choking them to death. When her pleas to spare Bruce’s life fall on deaf ears, Betty transforms and her and Wolverine engage in a brief but violent battle throughout the hotel. Although she manages to blind Wolverine in one eye, Logan uses his adamantium claws to impale Betty - taking out her internal organs until she agrees to transform back into her human form - then promises to call an ambulance if she puts on the collar. Betty again begs Logan to spare the man she loves, but he makes it clear he intends to kill Banner, informing her that if she tries to warn him, he'll slice her to pieces.
The mainstream Wolverine has a long history of violence, but it’s always been tempered by his moral code and sense of empathy. The Ultimate Wolverine doesn’t have those moral restrictions, and acts more like a killer and a thug than his mainstream counterpart. While he's taken - and dealt - more damage than in his battle with the Ultimate She-Hulk, Logan's seldom been crueler, and the way he ambushes Betty - and later Bruce - with a device specifically designed to inflict a torturous death depicts him not as the brawler fans know from the mainstream comics, but as a black-ops killer whose claws have never been sharper.
Although Logan states, "I don't like hurting girls," that doesn't seem to give him any pause in doing what seems to be permanent damage, nor does he even bother to pretend that he intends to spare Bruce Banner, even though that's what ultimately happens when the two meet again. Consciously edgy and depicting the Ultimate She-Hulk as nude throughout her clash with Wolverine, Ultimate Hulk vs. Wolverine embraced Logan's Ultimate Universe characterization as someone with a genuinely dark past very gradually being redeemed by the X-Men. While his first few rounds with the Hulk might have tested Logan's healing factor to its limit, it was his battle with She-Hulk that will go down as Wolverine's most vicious fight with a gamma-powered foe.