This study aims at exploring the theoretical perspectives and research related to second language teacher identities. In particular, this paper focuses on the studies on the identities of English teachers in the Korean educational system. Major findings are as follows: First, based on the previous literature on teacher identities, teacher identities are defined as dynamic, multidimensional, and changing, as they continuously interact with individual, social, and cultural contexts. Second, it was found that studies have focused on (1) the meta-analyses of English teacher identities, (2) native-speaking English teacher identities, (3) the identities of non-native-speaking English teachers co-teaching with native-English-speaking teachers, (4) the identities of non-native-speaking English teachers including pre- and in-service teachers, and (5) teacher identity development through teacher education activities. Lastly, this paper brings up issues and suggestions on the formation and development of English teacher identities. It also offers directions for the future research on professional identities of second language teachers.