Well, according to the Romford Recorder Henry VIII very nearly gave us Henry IX. This would have been his illegitimate son Henry Fitzroy, born to the king’s mistress Elizabeth Blount.
Henry Fitzroy is not fiction, but was born in 1519 in the Jericho Priory (see above image) at Blackmore, ten miles north of Romford. The above article states that at one point Henry VIII seriously considered making the illegitimate Henry Fitzroy his heir, brushing aside any legitimate female children the king had. This would have been Mary I, of course, and then Elizabeth I. But Henry Fitzroy died young, and then eventually Henry VIII sired Edward VI on Jane Seymour. Problem solved. For the time being at least, because Edward would also die young and Mary and Elizabeth would eventually reign anyway.
Well, I suppose that Henry VIII would only have been following in Tudor family footsteps…after all his father declared the illegitimate Elizabeth of York legitimate in order to marry her! So why not declare Henry Fitzroy legitimate in order to secure the succession in the male line? The Tudors were a little comme ci comme ça when it came to such inconvenient things.