While Wolverine has proven to be one of the most formidable heroes in the entire Marvel Universe, which is mostly due to his healing factor, even he can’t compete with a villain who has their own fast-healing power–one that is twice as powerful as Wolverine’s.
Wolverine aka James “Logan” Howlett was born a mutant in the late 1800s. Once his powers manifested, Logan was equipped with heightened animalistic senses, bone claws that emerge from his fists, and a healing factor that not only allows Wolverine to quickly recover from any injury but also elongates his life–making him far older than he appears. While he was born with these incredibly powerful abilities, Wolverine was later kidnapped by an organization known as Weapon X, and during his time in captivity, Logan had adamantium grafted to his entire skeleton, making him even more deadly than he was before. However, even with his unwanted upgrade, Wolverine still couldn’t hope to seriously harm this Marvel villain.
In Ultimate X-Men #60 by Brian K. Vaughan and Stuart Immonen, the evil mastermind behind the mutant experimentation that occurred within Weapon X, Dr. Cornelius, approaches a woman named Yuriko Oyama who had been in a terrible accident that left her paralyzed from the neck down. As it turned out, the X-Man Storm was evidently responsible for Yuri’s condition, something which filled Oyama’s heart with terrible vengeance. So, when Cornelius offered to restore her body and even make her superhuman in the process, Yuriko accepted and from that point on became the unkillable Wolverine villain known as Deathstrike. When Deathstrike tracked down Storm, Ororo was with Wolverine just as Yuriko knew she would be. Lucky for Deathstrike, Cornelius used Wolverine’s own DNA–which he had stored from his time at Weapon X–and used it to splice her genes with his, granting her a healing factor as well as claws of her own. However, Deathstrike wasn’t an exact copy of Wolverine as Cornelius was able to make a few upgrades to Logan’s mutant powers before gifting them to Yuriko, making her healing factor work twice as fast as Wolverine’s.
While that notion seems impossible or even a bit too convenient, it actually makes perfect sense given the landscape of the Ultimate Universe. Within this corner of Marvel’s multiverse, Weapon X is a much more developed entity than it was in 616 which allowed it to remain a main villainous entity for the X-Men throughout their Ultimate run. Given all the time and effort Marvel Comics put into making Weapon X a major threat in the Ultimate Universe, it only makes sense that the evil organization would improve overtime–resulting in the absolutely terrifying killing machine that is Deathstrike.
While Storm was defeated Deathstrike with a lightning bolt, Yuriko survives and is seen again as a prisoner of S.H.I.E.L.D. before successfully escaping, never to be seen again. Deathstrike disappeared from Marvel canon along with the decimation of the entire Ultimate Universe, which is perhaps the best thing that could have happened for the X-Men. While fighting Wolverine, Deathstrike took zero damage and used the weakness of Wolverine's healing factor, pain, against him. Deathstrike’s claws were also way deadlier than Wolverine’s as they had the ability to extend and wrap around Yuriko’s victims while also being razor-sharp. All-in-all, Deathstrike proved to be too much for Wolverine to handle, and while her claws were the main factor in her victory over him, it was her impossibly fast healing factor that really put her over the edge as it worked twice as fast as Wolverine’s iconic ability.