Given some of the common plot elements (including falsely accused allegedly false lovers and impersonation), Much Ado About Nothing has a number of possible sources.
Most critics believe the major source is Matteo Bandello’s group of stories, Nouvelle (which means “Tales”), published as early as 1554, and translated into English in the 1560/70’s. The twenty-second tale revolves around a nobleman named Timbreo who is fooled into thinking his fiancee is being unfaithful. Some of the contributing factors that point to this source are the name of the betrothed, Fenicia Lionato, and the location, Messina. The method of deception is similar as well: the groom-to-be sees a man in his lover’s window.
Another possible source provides the rejection of the bride-to-be: Ludovico Ariosto’s Orlando Furioso, an Italian epic poem published in 1532 and translated into English in 1591. In Book V of the poem, the lady Ginerva is rejected by her groom-to-be Ariodante after he sees her maid Dalinda meets her lover on the balcony while wearing Ginerva’s dress. Orlando Furioso also provides what could be the character of Benedick and his views on marriage.
It’s interesting to note that the plot elements Shakespeare took from his sources have faded from regular use, but what seems to be his invention, the Beatrice/Benedick merry war and wooing, has become the staple of the rom-coms of our day, from Cary Grant and Katherine Hepburn in Bringing Up Baby, through Bruce Willis and Cybil Shepherd in Moonlighting, to today, with Julia-Louis Dreyfus and James Gandolfini in last year’s Enough Said.