I am mainly an improvisor.
I played mad emperor Caligula in a roleplay with managers and CEO's of a big corporation. I was both amusing, dangerously mad and a very good process facilitator until I got 'murdered' ;-)
I played nasty people in trainings, to such grit, that one day I thought I went way too far, until the participants said: " that is exactly how our patients behave." I had never ever played aggressive patients on methadon before or even met.
I played a trailer park father who was losing everything, in a both funny and painful way.