The X-Men have introduced a number of incredibly powerful omega-level mutants over the years whose powersets have ranged from psionic to elemental and everything in between. However, there are quite a few mutants whose powers are physical in nature which leads to increased levels of super-strength.
It can sometimes be difficult to determine just how strong some of these characters are given the fluctuating nature of mutant abilities and the sometimes inconsistent way they've been written over the years. These ratings of X-Men characters are based on their strength class as determined by the tonnage they can consistently lift (Class 10=10 Tons).
10 Sunspot's Solar Form Gives Him Enhanced Strength That Has Grown Over The Years (Class 50)
When Roberto Da Costa first joined with the New Mutants as Sunspot, his solar form only served to increase his strength and durability by a small amount that averaged around Class 2. However, his powers have grown and been altered a few times over the years and this has greatly increased his strength levels.
By absorbing additional solar radiation, Sunspot has increased his strength to Class 50 with the potential to increase it even more, though he runs the risk of losing control of the absorbed energy if he pushes his powers too far.
9 Rockslide's Unique Geokinetic Form Granted Him Incredible Levels of Strength (Class 75)
Santo Vaccaro was still learning about his unique geokinetic energy form before he died during X of Swords. This power allowed him to recreate his body out of solid granite to become the super-strong Rockslide.
With each new version of his body that he created his strength continued to increase as did the size of his rocky form. It's possible that Rockslide could have continued to create larger and stronger forms if he had survived and aged to an adult, but even as a younger student, he was capable of easily lifting over 75 tons.
8 Strong Guy Absorbs Kinetic Energy And Can Increase His Strength Exponentially (Class 50-100+)
It's no surprise that Guido Carosella would be considered one of the X-Men's strongest mutants considering he chose the codename of Strong Guy. His mutant powers first activated when he was hit by a bus as a teenager, and he absorbed the kinetic energy of the impact changing his body's shape.
As Strong Guy, he can easily lift over 50 tons but he has the potential to increase his strength by absorbing more kinetic energy, though he again risks it leading to physical changes as his muscle mass is irreversibly increased.
7 Warpath's Strength Has Fluctuated Over The Years But He Is Still Very Powerful (Class 75+)
James Proudstar is the younger brother of the powerful mutant known as Thunderbird. Thunderbird died during one of his earliest missions with the X-Men, and James took on the name Warpath.
His natural physicality was originally enhanced to superhuman levels, though over the years he has pushed his abilities and greatly increased his strength and other powers. This has led to one of the X-Men's most inconsistently written power sets (he could even fly at one point), but at one time he was capable of lifting over 75 tons with the potential for even greater feats.
6 Colossus Can Transform Into Organic Steel Which Greatly Increases His Strength (Class 100)
One of the X-Men's strongest members has always been Piotr Rasputin/Colossus, whose mutant ability to transform his skin into organic steel also greatly increases his already impressive strength.
Colossus has consistently proven himself as the team's powerhouse and is capable of lifting over 100 tons on a regular basis, though he is capable of pushing himself further as well. His strength was increased even further when he temporarily became the avatar of Cyttorak and one of the possessed Phoenix Five, though he returned to his usual strength levels afterwards.
5 Juggernaut's Crimson Gem Of Cyttorak Can Enhance His Strength When Needed (Class 100+)
Cain Marko was transformed into the unstoppable Juggernaut after he discovered the Crimson Gem of Cyttorak, which made him the avatar for a demonic god who lived for destruction. Cyttorak empowered Marko with his strength and abilities that enabled him to take on some of the strongest members of the X-Men with ease.
While Juggernaut's current power levels aren't as strong as they used to be as he's rejected his connection to Cyttorak, he was still able to lift well over 100 tons and even draw on more power from the powerful entity if Cyttorak deemed it necessary.
4 Rogue Has Absorbed The Strength of Characters Like Ms. Marvel & Wonder Man (Class 100+)
While she first appeared in the pages of The Avengers as a member of Mystique's Brotherhood of Evil Mutants, she soon found a new home at Xavier's school where she eventually became a leader of the team and one of its most powerful members. She initially gained her powers after she absorbed the abilities of Carol Danvers/Ms. Marvel, which gave her incredible strength.
While her powers and absorbed abilities changed over the years, she has kept her strength up after absorbing Simon Williams/Wonder Man's ionic power. This makes her strength Class 100, though her absorption powers mean she could still increase that further if needed.
3 Gentle's Vibranium-Reinforced Body Has Yet To Test Its Strength's Upper Limits (Class 100+)
Nezhno Abidemi is a Wakandan mutant whose manifesting powers caused uncontrollable shakes and tremors that threatened to kill him before he could control his abilities, so he was tattooed with liquid vibranium to help ease his pain.
As Gentle, he is able to increase his muscle mass, and later his strength and size, though it comes with the potential cost of triggering the traumatic tremors. He has never really tested his strength's upper limits but is on a similar level as other X-Men like Colossus, but he could potentially outclass them if he was forced to exert himself fully.
2 Meggan Is Naturally Strong But Can Also Draw On Earth's Energies To Strengthen Her (Class 100+)
The metamorph known as Meggan is a former member of Excalibur who is surprisingly one of the most powerful mutants on the planet due to her mystical connection to the Earth. She has powerful empathic abilities as well as elemental manipulation, but she has increased strength and durability that make her capable of lifting over 50 tons.
However, her connection to the Earth allows her to draw extra energy to further power herself, which means she can lift well over 100 tons when needed while also powering up her other abilities. Meggan has largely retired to raise her family, but she still stands as one of the X-Men's strongest characters.
1 Apocalypse's Incredible Strength Can Be Increased By Absorbing Additional Energy (Class 100+)
The eternal mutant named En Sabah Nur is better known as Apocalypse. He was a long-time villain of the X-Men before he became one of the team's leaders during the Krakoan age. Apocalypse's powerful abilities have grown and evolved over the millennia that he has existed, enhanced by the Celestial technology he first discovered in ancient Egypt.
Apocalypse's incredible strength puts him above not just the X-Men but has allowed him to overpower the Hulk and other powerful characters. He can even increase his strength by absorbing additional energy, putting him in a strength category that is almost impossible to measure.