This Element aims to examine how language operates as power across the ecosystem of language teacher education (LTE). It maps how language-as-power (LaP) works at three layers: microsystem (teachers and classrooms), mesosystem (institutions), and macrosystem (socio-politics). Section 1 surveys LaP historically, tracing its historical evolution from Plato to contemporary theorists and showing how these ideas shape LTE. Building on this history, Sections 2-4 unpack LaP across ecological layers: microsystem, mesosystem, and macrosystem. Section 5 looks forward, analyzing AI's redistribution of power at each scale, and applying a 3Ps (possible, probable, and preferable) futurology to chart potential pathways. Anchored in experiences from the Global South, the Element argues that LaP in LTE needs awareness and action. It offers ideas on how to address these issues in LTE through solutions such as widening epistemic access, contesting monolingual norms, and institutionalizing dialogic, justice-oriented professionalism and trans-speakerism, to name a few.