Whilst not the first person who would come to mind when thinking of an Expressionist Painter, I believe that Ralph Steadman easily falls under this heading.
The Wiki definition of Expressionism is this:
"A style of painting, music, or drama in which the artist or writer seeks to express emotional experience rather than impressions of the external world."
I first came across his work when I read 'Fear and Loathing in Las Vegas" by Hunter S.Thomson - he illustrated some copies of this book.
Steadman was great friends with the writer, and Thompson's 'Gonzo' journalistic style, perfectly complimented the frenetic style of the artist.
So keeping in mind the definition of Expressionism, how does he show this emotion in his paintings?
Here is a still photo from the opera "Carmen"
Whilst it's a perfectly good image - it doesn't capture the passion of this opera, and the performance.
Now in comparison, check out Steadman's painting of the same theme, look at the energy and the movement expressed in the image:
He is famous for his caricatures as well, and these are just as powerful. I love these one of Walt and Jessie from Breaking Bad.
If you are interested in learning more about the artists, there is an excellent documentary about his life hosted by his friend, Johnny Depp, who was also friends with Hunter. S. Thompson.
It is called 'For no good reason", check out the trailer here: