Colossus is a big, strong ass dude but... frankly it seems like he gets beaten up a lot? Maybe not though.
 
I'm trying to find out what are Colossus's biggest weakpoints.. I'm guessing the biggest is he's completely vulnerable to telepathic attacks. Secondly, he's absolutely SCREWED if he faces off against Magneto or Polaris... Finally, steel isn't THAT durable... so anyone with Adamantium (Cyber, Sabretooth, Wolverine) or Vibranium (Warpath's knives) can totally cut him up...

"His biggest weakness is his love for his sister. "

he's vunerable to acids too

" His biggest weakness is his love for his sister. "

" @Jake Fury said:

"His biggest weakness is his love for his sister. "

Agree "

" he's vunerable to acids too "

I dunno. Honestly it seems like Colossus is WAY overrated.
 
Hell, a weak telekinetic could just hoist him up into the air and hold them there laughing...
He's strong as hell, yet still nowhere near Hulk/Juggernaut..
Warpath with Vibranium could cut him right up..
Telepaths can have their way with him..

Hes not totally immune to telepathy but in his metallic form he is more resistant to it. 
 
Magnetism is his BIGGESt weakness and being that their only a few UBER strong magnetism users hes got no real fears. 
 
But besides that his one true weakness is his heart, many times he will act upon his heart or react to something with his heart. 
 
Look at when kitty died, he was moppy and bitchy so he was of no use. And when his sister died of the legacy virus he was very emotional and stayed for quite sometime, even turning into a Alcoloyte because of her death and not seeing a reason to live anymore. 
 
His true weakness is his heart

" His biggest weakness is his love for his sister. "

" @Jake Fury said:

" His biggest weakness is his love for his sister. "

WHAT exactly does that mean?? "

" @Mr.Hulk_Smashin'! said:

" @Jake Fury said:

" His biggest weakness is his love for his sister. "

WHAT exactly does that mean?? "

in short. he meant anything happens to his sister Piotr will react.  "

" @Jake Malcom said:

" @Mr.Hulk_Smashin'! said:

" @Jake Fury said:

" His biggest weakness is his love for his sister. "

WHAT exactly does that mean?? "

in short. he meant anything happens to his sister Piotr will react.  "

Exactly. I'd feel the same for my sister. But it can be a serious weakness if a villain decides to use it against him.  "

" I dunno. Honestly it seems like Colossus is WAY overrated.  Hell, a weak telekinetic could just hoist him up into the air and hold them there laughing... He's strong as hell, yet still nowhere near Hulk/Juggernaut.. Warpath with Vibranium could cut him right up.. Telepaths can have their way with him.. "

I know in the Ultimate universe Wolverine opened him up with his claws but in the 616 has that ever happened? 
 
His skin is always described as "organic steel" which I've always thought has different properties to regular steel.
 
And yeah his biggest weakness is that he cares.

" I know in the Ultimate universe Wolverine opened him up with his claws but in the 616 has that ever happened?   His skin is always described as "organic steel" which I've always thought has different properties to regular steel.  And yeah his biggest weakness is that he cares. "

His brain / mind is his biggest weakness.

Super Magnets...

" @MisterDK said:

" I know in the Ultimate universe Wolverine opened him up with his claws but in the 616 has that ever happened?   His skin is always described as "organic steel" which I've always thought has different properties to regular steel.  And yeah his biggest weakness is that he cares. "

i heard it has more in common with osmium then steel or iron  "

" His biggest weakness is his love for his sister. "

Colossus has never really been at the high end of strength or durability.  He's always been behind guys like Hulk or Juggernaut.  I think he was designed that way on purpose.  Initially, none of the X-Men or the Giant-Size X-Men were particularly powerful.  Of that group, only Storm, Jean, and Iceman have really seen big boosts in the last 30 years.

Vibranium

colossus broke vibranium
they had him cuffed in virbranium bonds and tried to melt him but he broke it to pieces

colossus broke vibranium
they had him cuffed in virbranium bonds and tried to melt him but he broke it to pieces

" @Jake Fury said:

" @Jake Malcom said:

" @Mr.Hulk_Smashin'! said:

" @Jake Fury said:

" His biggest weakness is his love for his sister. "

WHAT exactly does that mean?? "

in short. he meant anything happens to his sister Piotr will react.  "

Exactly. I'd feel the same for my sister. But it can be a serious weakness if a villain decides to use it against him.  "

Yep which even though it was insanely sad i think killing Illyanna off first time and Kitty was a great idea. (plus kitty was f@#king annoying nowadays) "

I would say Collosus's biggest weakness over the years has been unimaginative writing. For how powerful and formidable he is more often than not he is written as a light weight.  
Capable of lifting tons and tons and tons, nearly invulnerable to physical attack, self sustained in metal form no need for food or air even.........with that powerset, you would think he would be a bigger factor.....but it seems he is consistently demoted to a catapult for Wolverine. 
 
He is definitely slept on.

" In 616 its never been shown to happen to him. Logan has attacked him a few times once in a mind controlled full on rage mode and all it did was send up sparks but Logan's never actually cut him up or scratched him with his claws to date. In Ultimate, they originally had it the very same way but when the banshee story arc came up (an utterly crappy story by the way) Logan can magically slices him open this time. "

I recall in X-Men: Evolution, when Colossus was serving as one of Magneto's acolytes, Magneto threatened him with his magnetism: lifting him up in the air to show him who's boss. But then something surprised me, something everyone has probably thought of but just doesn't happen when the situation presents itself. Colossus assumed his normal physique and quickly recovered, picked Magneto up by the throat and proceeded to slam him the master of magnetism into the nearby wall.

it's not really steel it's much harder his biggest weakness is he's a nice ass guy

"Hes not totally immune to telepathy but in his metallic form he is more resistant to it.  Magnetism is his BIGGESt weakness and being that their only a few UBER strong magnetism users hes got no real fears.  But besides that his one true weakness is his heart, many times he will act upon his heart or react to something with his heart.  Look at when kitty died, he was moppy and bitchy so he was of no use. And when his sister died of the legacy virus he was very emotional and stayed for quite sometime, even turning into a Alcoloyte because of her death and not seeing a reason to live anymore.  His true weakness is his heart "

" His obsession with his sister is really creepy "

"@redbull:
carbondonium too i would think too...and i thought he was invulnerable from telepathy in his armored form? either way he is incredibly tough 
 

    "

His greatest weakness is his "little snowflake" (I think he is the only one who still believes that Magik isn't completely twisted and evil).