Has there ever been a monarch that wrote a book with his or her memoirs!?

i already knew about the duke of Windsor and his 'thing' mate. i'm talking about a monarch that was reining while the book was in circulation. i'm dreaming huh! has such a book ever been written? oh..what mesmerizing reading a book would be if Queen Elizabeth II penned a book. will her diary ever in the future be made accessible to historians?. why does her majesty use pencil rather than pen for her diaries.? ..let me get a little daff..was 'my secret life' written by a royal?