He is a 'madman' out on the ski slopes. [=he is an extremely daring or reckless skier]
He drives 'like a madman'. [=he drives very recklessly]
a celebrity being stalked by a 'madman'
(..) There's no mission. Oh, shit. Shit. You're not real! You are not real! Is this what you are, soldier? Some useless ghoul? The local madman? - I'm not a soldier. - You'll end up in a cell! Old, worthless, discarded. There's no mission. While you rock and drool, (..)2001 A Beautiful Mind