I'm sure there is a thread about him here but I can't find him either. He was certainly a fascinating and unusual character-- the close friendship with the Empress Elizabeth of Austria (Sisi) his second cousin, broken engagement to her sister, his sexual orientation, the tempestuous relationship with Richard Wagner, his compulsive castle building and mysterious death. The debate about his mental condition at the end of his life too, of course.
There are several good biographies on Ludwig, in English. I enjoyed The Mad King by Greg King but read it so long ago that I've forgotten most of it, lol.
An overview of Ludwig's life here, from Unofficial Royalty.
King Ludwig II of Bavaria | Unofficial Royalty