There are few people or objects Wolverine's claws can't cut through, but against Mr. Fantastic's extraordinary stretching powers, the adamantium weapon can barely make a scratch. In a few Marvel Comics encounters, the Fantastic Four's Reed Richards proved to be the ultimate Wolverine-stopper as he was immune to his claws. Most notably, the time when the genius-level hero continually stretched his body so that Logan couldn't break free, no matter how many times he tried to tear him apart.
Mr. Fantastic's stretching powers allow him to do amazing things, as he can contort and extend his body to extreme lengths and positions. Among his many power uses, Reed Richards can shift his body around to sneak through cracks, spread his arms (and other body parts) to reach places he couldn't get to in his usual form, and tie his arms around an opponent's body like a knot to keep them in place. However, one of the most incredible ways the Fantastic Four hero has stretched his body is when he turned it into a giant trap specifically designed for Wolverine, making him immune to his claws.
In Wolverine #22 by Mark Millar, John Romita Jr., Klaus Janson, Paul Mounts, and Chris Eliopoulos from Marvel Comics, Logan was turned into a weapon against his will by Hydra, the Hand, and the Dawn of the White Light. The evil organizations planned on turning Wolverine into a meta-human killing machine, leading some of Earth's Mightiest Heroes to stop him before more blood was spilled. However, Wolverine breaks into Fantastic Four's HQ, where they spar with the brainwashed hero. After he causes significant damage, Mr. Fantastic traps him by stretching his skin and covering Wolverine. Logan tries to stab through Reed Richard's skin, but his attacks are useless since it continues to extend. Mr. Fantastic makes him immune to Wolverine's claws.
The moment is a call-back to a similar defensive tactic on Wolverine from Mr. Fantastic. In Fantastic Four #374 from Marvel Comics, Wolverine took on Reed Richards and was similarly trapped as he covered his entire body with his own. In that case, Mr. Fantastic revealed Wolverine's claw swipes were simply wasting time, as his body became malleable enough to resist being penetrated.
It might seem like a silly way to put an end to Wolverine's attacks, but Mr. Fantastic going malleable and continually expanding makes him immune to Wolverine's claws. Logan only broke free after being teleported; otherwise, he was trapped with no way to get through Reed Richards' body.
Considering the Fantastic Four hero has successfully used his stretching powers twice to stop Wolverine, the Avengers should be quick to call the hero if the clawed mutant ever loses control again. Mr. Fantastic is the perfect Wolverine stopper in the pages of Marvel Comics, even if it's not the most glamorous or cool technique to do so.