2. Jack Nicholson - The Shining
Jack Nicholson has always had a reputation over his lengthy and storied career as being able to play manic intensity with ease and often needs reigning in by directors when he steps a little too far. Here, his unpredictability and insanity works massively to his favour in his iconic role of Jack Torrance in Stanley Kubrick's The Shining. When Torrance finally descends into madness, Nicholson is the perfect choice to display over-the-top madness, whilst also maintaining the ability to make the audience sympathise with the tortured man. What's so great about Nicholson's performance is that he pushes himself so much further and experiments with things no other actor would, and adding that to Stanley Kubrick's quest for perfection through hundreds of takes and you have one of the most gloriously unstable performances ever captured by film. The infamous "Here's Johnny!" moment was also improvised by Nicholson, and despite it being one of the most well-known scenes in film, it is still an intense and sinister moment in Kubrick's horror masterpiece. Nicholson has never been more bonkers and brilliant than he is here, and his performance is the perfect example of over-the-top acting done well.