This companion brings together a diverse set of concepts used to analyse dimensions of media disinformation and populism globally. The Routledge Companion to Media Disinformation and Populism explores how recent transformations in the architecture of public communication and particular attributes of the digital media ecology are conducive to the kind of polarized, anti-rational, post-fact, post-truth communication championed by populism. It is both interdisciplinary and multidisciplinary, consisting of contributions from both leading and emerging scholars analysing aspects of misinformation, disinformation and populism across countries, political systems and media systems. A global, comparative approach to the study of misinformation and populism is important in identifying common elements and characteristics, and these individual essays cover a wide range of topics and themes, including: fake news, mediatisation, propaganda, alternative media, immigration, science, and law-making, to name a few. This companion is a key resource for academics, researchers and policy-makers as well as undergraduate and postgraduate students in the fields of Political Communication, Journalism, Law, Sociology, Cultural studies, International Politics and International Relations.