Herobrine plugin.

I was on a server and there was treasure chests in which I obtained a stack of diamonds while I was at a small island getting food. herobrine was hiding from me behind a tree. Next thing I new a creeper blew me up. my question IS there a herobrine plugin in multilayer that makes herobrine randomly show up? (I was playing on a server when I saw him)

can some one let me know, I just wanna know just in case I actually saw herobrine.