From the Artstor Blog:
Open Artstor: Folger Shakespeare Library is now available with a selection of more than 8,000 images from the Digital Image Collection of the Folger Shakespeare Library. Provided under Creative Commons licenses, these images illuminate the history and output of Shakespeare and theater in general, from illustrated manuscripts and rare books, costume and stagecraft, to actors’ portraits and miscellanea. This is part of our new, free initiative to aggregate Open Access museum, library, and archive collections across disciplines on the Artstor platform — already a destination for scholars using visual media.
Note: As of October 10, 2019 Open Artstor/Artstor Public Collections provides access to more than 1.21 million images.