Richard Dadd (1817-86), an English artist who is best remembered for his fairy paintings, killed his father in the belief that he was the Devil and spent most of his life in the Bethlem lunatic asylum. The institution seems have been tolerably humane by that time, and he was able to continue with his painting. This is a striking portrait of Sir Alexander Morison (1779-1866), the Scottish physician and alienist (what a wonderfully Victorian word) who was ultimately responsible for his care. He was chief physician at Bethlem for a time and was regarded as a leading expert on mental disease; this is a book that he published in 1826 on mental disorders and their treatment:
He was also a successful society doctor, becoming personal physician to Princess Charlotte (the daughter of George IV) and her husband Leopold of Saxe-Coburg-Gotha. So he seems to have moved with ease between very different worlds and sounds a most interesting character.
There is something weird about those female figures at the back, they alone might make one suspect that the painter might be a bit unbalanced. The obsessive detail in his fairy paintings is a stronger sign.
Here is one of Dadd's more typical paintings, a Shakespearian fairy scene, Titania Asleep, 1841: