Thomas Kyd is traditionally accepted as the author of The Spanish Tragedy, Soliman and Perseda, and Cornelia. HeKyd may also have written a lost Hamlet play that preceded Shakespeare’s version. Among his contemporaries, Kyd enjoyed a far higher reputation than he does today. Thomas Dekker and Ben Jonson’s respective epithets, ‘‘industrious’’ and ‘‘sporting’’, suggest that Kyd’s canon was considerably larger than the three plays now acknowledged as his, and that he may have written comedies. This introduction argues that Kyd’s canon should be expanded from three surviving sole-authored plays to six, including King Leir, Arden of Faversham, and Fair Em. Furthermore, the introduction engages with arguments that the play, The First Part of Hieronimo, represents a reconstruction of a lost Kyd play called The Comedy of Don Horatio, and that Shakespeare, rather than Kyd, was responsible for a lost Hamlet play (the so-called Ur-Hamlet) of the late 1580s. The introduction therefore engages with the attribution and textual histories of each of these plays, and explores the dramaturgical similarities amongbetween the six plays that have been attributed solely to Kyd.