maniac

A psychotic or otherwise mentally ill person who exhibits violent or bizarre behavior. Not used in psychiatric diagnosis.

A person who has an excessive enthusiasm or desire for something.

A person who acts in a wildly irresponsible way.

Raving with madness; mad or crazy; insane.

One who raves with madness; a madman.

Raving with madness; raging with disordered intellect; affected with mania; mad.

A raving lunatic; a madman.

An insane person, especially one who suffers from a mania.

A fanatic, a person with an obsession.