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'
(..) All has turned to vain ambition. He would even use his grief as a cloak. A thousand years this city has stood. Now, at the whim of a madman, it will fall. And the White Tree, the tree of the king... ...will never bloom again. Why are they still guarding it? (..)2003 The Lord of the Rings: The Return of the King