In the play "Merry Wives of Windsor" is a character Dr. Caius, who is a physician. He came from abroad, was extremely quarrelsome and hated Welshmen.
There was actually a Dr. Caius, a professor at Cambridge, who, according to the Dictionary of National Biography, was a physician, came from abroad, was extremely quarelsome, and hated Welshmen.

Is this a coincidence? The real Dr. Caius of Cambridge died in 1573, when Will Shakesper was nine years old, so he could not have known the Doctor, and yet the characters of Dr. Caius in "The Merry Wives" and the real Dr. Caius are identical. It must be remembered that Francis Bacon entered Cambridge University during the year in which Dr. Caius died.
Is it a coincidence that the real Dr. Caius of Cambridge, whose exploits would be known to Francis Bacon as a student at Cambridge, is ridiculed under his own name in "The Merry Wives of Windsor?" The peculiarities of Dr. Caius could hardly have been known beyond university circles, as there were no newspapers in those days, and there is no evidence that Will Shakesper had ever been to Cambridge or knew anyone there.