My friend and i was playing Left 4 Dead and then suddenly my friend said there was a ''Killer'' nearby.He told me it hurts you and make you fall onto the ground in 2 hits,and kills you in 7 hits.Now is there a such thing as a killer in Left 4 Dead?

There definitely isn't a type of special infected called killer.

Nope lol. Sounds kinda like the hunter to me.

Your friend is not to be trusted

Their all killer zombies dude. I would be more worried if your friend told you there was a peace loving vegan zombie.

It's a Witch but that gets you down in like 1 hit. And the Hunter definantly gets you down in 1 hit. Maybe he's talking about the Tank.

" It's a Witch but that gets you down in like 1 hit. And the Hunter definantly gets you down in 1 hit. Maybe he's talking about the Tank. "

No dude.  The only enemies in L4D are:

Normal Infected
Smokers
Boomers
Hunters
The Witch
The Tank

All are shown in the opening cinematic.  Your "friend" is either playing with mods, or a dirty rotten liar.

no such thing

Not real, your friend is full of crap or using mods.

Or your friend has no clue what he's talking about.  My friends can't get the names straight for their own lives.

" It's a Witch but that gets you down in like 1 hit. And the Hunter definantly gets you down in 1 hit. Maybe he's talking about the Tank. "

a killer? if you're going to be fooled with fake zombies, at least let them have decent names

Drop kick your friend.

Your friend is stupid.

your friend is full of crap

" Your friend is stupid. "

Sounds like he got one type confused with another. Or he's lying. Just ask him. Your not really friends if you can't be honest with each other.

" It's a Witch but that gets you down in like 1 hit. And the Hunter definantly gets you down in 1 hit. Maybe he's talking about the Tank. "

Let's go back to insulting your friend.
 
Your friend is wrong and he's an idiot.

" Let's go back to insulting your friend.  Your friend is wrong and he's an idiot. "