Primary text(s):

The text of the second French edition, the Theatre des cruautez des hereticques de nostre temps (Antwerp, 1588), is available on GallicaLink opens in a new window and on Google BooksLink opens in a new window (copy from the University of Ghent).

You may also download high-resolution PDFs of the copies of the Latin and French editions held by The Johns Hopkins University (courteously provided by Prof. Earle Havens, Curator of Rare Books, Sheridan Libraries, JHU):

• Verstegan, Richard, Joannes Bochius, and Adrianus Huberti, Theatrum Crudelitatum Haereticorum Nostri Temporis (Antwerp: Adrien Hubert, 1587) (Baltimore, Maryland, The Johns Hopkins University, George Peabody Library: 274.06 V616 1587 c. 1)
• Verstegan, Richard, [Joannes Bochius], and Adrien Hubert, Theatre des Cruautez des hereticques de nostre temps : traduit du latin en françoisLink opens in a new window (Antwerp: Adrien Hubert, 1588). (Baltimore, Maryland, The Johns Hopkins University,George Peabody Library: 272 V616 1588 c. 1)

Note that these PDFs are very heavy files!

Modern edition and partial translations:

•  Le Théâtre des Cruautés de Richard Verstegan (1587), ed. by Frank Lestringant (Paris: Chandeigne, 1995).

You may also like to consult:

• Barbara Diefendorf, The Saint Bartholomew's Day Massacre : A Brief History with Documents (Boston, Massachusetts: Bedford / St. Martin's, 2009), chapter 33.
• Study aid: English translations of the French verse accompanying the woodcuts of Verstegan's section on Huguenots 

Further reading:

• Paul Arblaster, 'Verstegan, Richard'Link opens in a new window, Oxford Dictionary of National Biography, 2004
• Michael Meere, 'Theatres of Torture: Martyrs, Pagans, and the Politics of Conversion in Early Seventeenth-Century France', Early Modern French Studies (previously Seventeenth-century French Studies), 37.1 (2015), 14-28. Available on-line via Warwick University Library.
• Romana Zacchi, 'Words and Images: Verstegan's "Theatres of Cruelties"', in Zacchi, Romana and Massimilano Morini (eds), Richard Rowlands Verstegan: A Versatile Man in a Age of Turmoil (Turnhout: Brepols, 2012), pp. 53-75. [ON ORDER FOR THE LIBRARY]