Arthur Conan Doyle

A good thing too because the author was a bit of a fruitloop who made a fool of himself chasing after fairies and such.

The White Company is quite good, haven't read anything else by him though

The Professor Challenger novels are fun. Shows his kookier side.

There was that dinosaur thing

He wrote a decent amount about spiritualism.Was pretty big into it. See "The Edge of the Unknown", etc. According to wikipedia, he was also involved in Freemasonry but became irritated with the constant debunking of spiritualism by his brothers so left the order.