Sham's The Enemy Within
Baron Ludwig von Wittgenstein
"And Wittgenstein was a beery swine"
Baron Ludwig had mutated into a cockroach-like creature and thus kept himself hidden in a side tower of Castle Wittgenstein, playing organ music for his “friends,” tens of thousands of small cockroaches that shared the tower with him. The party found him to be entirely civil and pleasant, if a bit naive about the affairs of his family, and they spared his life. However, he was presumably killed in the subsequent destruction of the castle.