What kind of weapon is the knight using exactly? Is he using a great sword, or perhaps a sword and shield combination? If the knight has a sword and shield the chances of winning would probably be a 50% chance for both the ninja and knight. Ninjas are much, MUCH faster then the knight,but if the knight has a sword and shield then there is a possibility that he could swing his weapon before the ninja is able to knock off his helmet(or at the very least block). Still ninja's are fast and can dodge efficiently, even in close quarter combat, so even if the knight does swing there is a chance that the ninja will dodge. Alternatively if the knight blocks then he will have a chance to swing his sword, but since I'm assuming the knights sword is super long, the ninja can maybe be able to back away before that happens, given his heighten senses and superior speed. There are too many factors and chances that are determined by luck in the fight, that I can not make a decisive decision.

Citation needed

The ninja can always come up from behind and just snap his neck, simple as that.

If you can find a way for him to snap the knight's neck through armor, I'll believe you.

I saw an opining in that armor.
the red cloth.
the ninja stabs the knight in that area(easy for a ninja given his speed,agility and cunningness)rendering both of the knight's arms useless.
then he takes the helmet off,and then kills him.(snaps neck,slits throat etc.....)

This conversation seems very biased.
A) The helmet is not so easy to take off as all of you seem to believe, even assuming the knight just sits there and lets him do it.
B) The ninja's gonna have a tough time stabbing the knight in a very precise spot in the middle of combat.
C) Even if the ninja did somehow miraculously manage to disable both of the knights arms, the knight would still be far from through. http://www.youtube.com/watch?v=zKhEw7nD9C4

A)I agree the helmet wouldn't be that easy to take off, but isn't that exaggerating a little? If the knight is just sitting there then it would be as easy as grasping the two sides of the helmet and pulling it off.
B)Ninja's are specifically trained to be as precise and agile as possible during combat. Any opening no matter how small shouldn't be as difficult to strike, even in the middle of combat.
C)Uh...okay I'm pretty sure that was a joke.
I still would like to know the outline of the knights armor and what weapon he/she is using for me to come to a decisive choice.

Well, to start off, underneath the plate-mail a knight would often wear another layer of chain-mail if they are "fully armed". For weapons, they generally had many choices. There were single-handed swords, hand-and-a-half swords, two-handed swords, shields, morning-stars, crossbows, halberds, battle-hammers, battle-axes, and probably a few others.

I'd have to say Ninja. Most armor is weak at the back of the knees, so if a ninja were to slash one or both of the knees that would render the knight immobile or close to is at the wounds progressively got worse through out the fight. This would then leave the ninja able to take more time and formulate a plan. However the knight would be able to fend off future attacks with his sword when he is immobilized. The ninja would then either execute a well thought out plan or let the knight bleed to death by taunting the knight and reopening his wounds. The ninja would also be able to make minor hits every now and then in any situation even if they are not lethal.

It depends on how the ninja approaches the knight.
And besides,the knight is very well he won't fall for some cheap taunts.so if his wounds close it's only a matter of time untill one of them makes a mistake.
The way I see it...it's fifty-fifty.

Poison smoke bombs!

I say Knight.

Yup, I say knight too. Awesome armour is awesome

Well if its the (Dark Night/Batman) (September 11, 2004 - March 22, 2008) then ...no

This is one of the better threads I've seen in a while.

But yeah, knight. Without stealth and an unarmored target, the ninja wouldn't be able to pull a kill off.