It's been hypothesized a great deal that Henry VIII was grooming Fitzroy to be his heir, & may have legitimicized him eventually had the boy not grown fatally ill. I can think of bastards who've been crowned king (William the Conqueror leaps to mind; Isabella's half-brother Henry of Trastamara is another), but I can't think of any who took the throne with daddy's prior approval.
I'm amazed Charles II did not name Monmouth (or any of his legion of bastard boys, really) as his heir, knowing the anathema the English people had for Catholics in general & his brother James in particular. I think that would have been a moment in time where the populace would have thrown their caps in the air & cheered over it.
Charles also stubbornly refused (unlike Henry) to divorce Catherine of Braganza for her inability to present him with a living child, which might also have been a popular move with the people, considering everyone knew of "Old Rowley's" prolificy outside the marriage bed.
What reason could Charles have had for making these two choices, especially when he had to know what his brother's reception as king would be? Opinions?