The old theory was that he suffered from syphilis, which used to be known as "The Great Pretender" because it could produce so many symptoms. I don't know if anybody's dug up ol' Henry, but syphilitic lesions on bones are diagnostic.
During Henry's reign, roughly 70,000 of his subjects were executed for various offenses, most of them petty. England's population at the time was a mere 2.5 million, meaning roughly 3% of its people died doing the Tyburn jig or the cold block chop.
I think that I read somewhere that most historians are now saying he probably did not have syphillis. Coincidentally, the king of France while Henry was king of England did suffer from syphillis and they shared at least one mistress (Mary Boleyn Carey Stafford).
I’ve read every book that I can find that deals with the wives of Henry VIII, but I think my favorite wife has to be Anne Boleyn.