Melville claimed to have spent four months living with the cannibalistic Typee people. There is definitely some truth in the story, though it's impossible to know just how much. (Source)
On his passport, Melville's forehead and mouth were classified as "medium." His chin was classified as "round," and his face as "oval." (Source)
In the opera of Billy Budd, the libretto part is written by acclaimed 20th century novelist E.M. Forster.