This is a comprehensive introduction to one of philosophy's deepest and most fascinating puzzles, the Liar Paradox. It introduces key theories of truth and paradox, and combines accessibility with depth, tracing the paradox from its simplest formulations to the most sophisticated contemporary theories. Chapters by leading philosophers and logicians present both classical and non-classical approaches - supervaluationist, paracomplete, paraconsistent, and substructural - and examine broader families of paradoxes alongside general theories of paradoxicality. The volume also explores the paradox's connections to meta-mathematics, modality, vagueness, quantifiers, context-dependence, and natural language semantics, demonstrating its far-reaching significance and its central role in logic, philosophy of language, and theoretical linguistics. Structured for clarity, each chapter introduces key ideas and develops advanced arguments, making the book an essential resource for students, researchers, and professionals seeking a comprehensive understanding of semantic paradoxes and theories of truth.