Anthony Giddens, Baron Giddens (born 18 January 1938) is an English sociologist who is known for his theory of structuration and his holistic view of modern societies. He is considered to be one of the most prominent modern sociologists and is the author of at least 34 books, published in at least 29 languages, issuing on average more than one book every year. In 2007, Giddens was listed as the fifth most-referenced author of books in the humanities. He has academic appointments in approximately twenty different universities throughout the world and has received numerous honorary degrees.

Four notable stages can be identified in his academic life. The first one involved outlining a new vision of what sociology is, presenting a theoretical and methodological understanding of that field based on a critical reinterpretation of the classics. His major publications of that era include Capitalism and Modern Social Theory (1971) and The Class Structure of the Advanced Societies (1973). In the second stage, Giddens developed the theory of structuration, an analysis of agency and structure in which primacy is granted to neither. His works of that period, such as New Rules of Sociological Method (1976), Central Problems in Social Theory (1979) and The Constitution of Society (1984), brought him international fame on the sociological arena. The third stage of Giddens's academic work was concerned with modernity, globalisation and politics, especially the impact of modernity on social and personal life. This stage is reflected by his critique of postmodernity and discussions of a new "utopian-realist" Third Way in politics which is visible in The Consequences of Modernity (1990), Modernity and Self-Identity (1991), The Transformation of Intimacy (1992), Beyond Left and Right (1994) and The Third Way (1998). Giddens' ambition was both to recast social theory and to re-examine our understanding of the development and trajectory of modernity.

In the most recent stage, Giddens has turned his attention to a more concrete range of problems relevant to the evolution of world society, namely environmental issues, focussing especially upon debates about climate change, analysed in successive editions of his book The Politics of Climate Change (2009); the role and nature of the European Union in Turbulent and Mighty Continent (2014); and in a series of lectures and speeches also the nature and consequences of the Digital Revolution.

Giddens served as Director of the London School of Economics from 1997 to 2003, where he is now Emeritus Professor at the Department of Sociology. He is a life fellow of King's College, Cambridge.