Tommy Udo.
https://youtu.be/S_0xAbFAIbM?t=169
The Sainted Peter O'Toole as the 14 Earl of Gurney
https://youtu.be/1p1tnvdx9JU?t=46
Sir Anthony ... I am not sure if Hannibal Lector is mad or just touchy
https://youtu.be/He1MTYvyUes?t=63
Mickey and Mallory ...
https://youtu.be/dH1QmfQnWbg?t=55
I always thought Juliette Lewis had some madness around the eyes
A bit of the old ultra violence
https://youtu.be/kTuuXL8lakE?t=46
John Malkovich as Tom Ripley in the sadly under appreciated Ripley's Game. If you haven't seen this, do.
https://youtu.be/eGxZS0r7pNw?t=230
And the new love of my life, Helena from Orphan Black, mad as a hatter

n.b. if Helena had more polish, she'd be Tom Ripley.
No, no Heath Ledger because that was an actor playing a lunatic. Too "commercial".