Researchers have long studied how the ideology of political leaders affects policymaking and social welfare. The limited coverage of cross-country ideology datasets, however, has meant that researchers have mainly focused on Organisation for Economic Co-operation and Development (OECD) countries. This letter therefore presents the Global Leader Ideology dataset, which vastly expands the scope of previous datasets by classifying chief executives as leftist, centrist, rightist or non-ideological in 182 countries annually from 1945 or independence to 2020. The letter describes the dataset's contents and coding, compares it to existing datasets, and illustrates its uses by exploring how the ideologies of political leaders differ around the world and over time. The letter thereby outlines a research agenda on the global causes of chief executives' ideologies and their effects on policies and socio-economic outcomes.