  After an overview of the use of digital shadows in computing science research
projects with cultural and social impacts and a focus on recent researches and
insights on virtual theaters, this paper introduces a research mixing the
manipulation of shadow avatars and the building of a virtual theater setup
inspired by traditional shadow theater (or ``castelet'' in french) in a mixed
reality environment. It describes the virtual 3D setup, the nature of the
shadow avatars and the issues of directing believable interactions between
virtual avatars and physical performers on stage. Two modalities of shadow
avatars direction are exposed. Some results of the research are illustrated in
two use cases: the development of theatrical creativity in mixed reality
through pedagogical workshops; and an artistic achievement in ''The Shadow''
performance, after H. C. Andersen.
