TheatreHistory.com - from ancient to contemporary - comprehensive; includes articles, background information & links to further resources. They do cite the sources of the articles (journals, etc.). Beware of the advertising.

Centre for Research in Early English Drama | Records of Early English Drama (REED)
" REED examines the historical MSS that provide external evidence of drama, secular music, and other communal entertainment and ceremony from the Middle Ages until 1642, when the Puritans closed the London theatres."

Comédie-Française , French Version, English version

English Actors at the Turn of the Century

Kabuki for Everyone

Masks - archive of mask images organized by country and culture

Royal National Theater in London

Theatrales
Links to French drama texts, most of which are in French. From the University of Quebec.

U K Drama Home Page