No, I mean like a Hero unit.
It's almost like an RPG character, but in RTS mode.
What WC3 stole... errr... tried to do and failed.
Unlike the 1337 unit you get in WC3, the Hero (while VERY versitile based on what race/class and skills you take.. plus equipment ) is either very powerful or pretty weak depending on how you build it... but it's never an "uber" unit, and can still get taken down by a horde.
It's something to supplement your game, not replace your army.