In this article we address the question: "What sub-identities of teacher educators emerge from the research literature about teacher educators and what are the implications of the sub-identities for the professional development of teacher educators?" Like other professional identities, the identity of teacher educators is a construction of various aspects or facets, which we prefer to call sub-identities. We are interested to learn what sub-identities might constitute the main identity of what we generically refer to as "teacher educators" and, to achieve this, we set out to analyse the research literature relating to teacher educators to search for ways in which such sub-identities might be explicitly or implicitly described. Based on the research literature we found four sub-identities that are available for teacher educators: schoolteacher, teacher in Higher Education, teacher of teachers (or second order teacher) and researcher. We also found a view on teacher educators as teachers in a more generic way. There seems to be a broad understanding that teacher educators have to transform their identity as teachers to become "teachers of teachers in Higher Education" and (increasingly) to become researchers of teaching and teacher education. The development of these sub-identities depends on the context of teacher education in various national and institutional contexts and the development of teacher educators over time. (Contains 3 figures.)