<p>The 'Comedy of a Duke of Ferrara' is a title of convenience for a lost play associated with the <em>Englische Kömedianten </em>in Germany in 1604. It appears to be linked to an extant German play, <em>Tiberius und Annabella</em>, and therefore to John Marston's <em>The Fawn</em>. This essay discusses a hitherto unnoted reference to the play in English print. The allusion acts as an anchor for all the other records and has implications, not just for the 'Comedy of a Duke of Ferrara', but also for <em>Tiberius und Annabella</em>, <em>The Fawn</em>, and — arguably — Shakespeare's <em>Measure for Measure</em>.</p><p><span style="font-size: medium;"><br style="font-size: medium;" /></span></p>