Finally The Myth Is Gone

Ugh.
"Notch has confirmed that Herobrine is a fictional character and isn't actually featured in Minecraft.

Quote (Notch): 'Ok ok. To be honest, there has never existed a Herobrine. It was just a rumor started by some douche and then someone probably created a mod.',
Kappische (Mojang)."

-Minecraft Explorer Pro

 

Ever heard of command blocks or plugins?

 

I don't see any proof that there was no plugins/command blocks.

 

You see, this Map uses command blocks. Anyone can easily do that with command blocks.

 

Herobrine doesn't exist in vanilla Minecraft.
It's not hard to understand.
Your screenshot was the result of a command block system.
Herobrine doesn't even exist in the game files.
sigh

 

It's an adventure map, updated to 1.7.4.
Therefore it has command blocks, therefore any claims of Herobrine existing because of this map are falsified.
It can simply be a zombie with increased damage and a name.
/summon Zombie ~ ~2 ~ {ActiveEffects:[{Id:5,Amplifier:50,Duration:1000,Ambient:1},{Id:12,Amplifier:50,Duration:1000,Ambient:1}],CustomName:Herobrine,CustomNameVisible:50}
Put this in a command block and you get a zombie named Herobrine. Said zombie will chase the player like a normal zombie, and due to its strength effect will kill in 1 hit. Also, it will not burn in the sun due to its fire resistance effect. And of course, with additional NBT tags, you could get a zombie with a Herobrine head.

 

Look at BrawlerAce_'s post..

 

If you are still doubtful, here is a command that spawns the entity exactly as you described it.
/summon Zombie ~ ~2 ~ {ActiveEffects:[{Id:5,Amplifier:50,Duration:1000,Ambient:1},{Id:12,Amplifier:50,Duration:1000,Ambient:1},{Id:14,Amplifier:50,Duration:1000,Ambient:1}],Equipment:[{id:276},{},{},{},{Damage:3,id:397,tag:{SkullOwner:"Herobrine"}}]}

Again, use in a command block; it's too long for chat