What major work is Sir Thomas More known for?

Sir Thomas More is best known for his work titled "Utopia," published in 1516. This book is a seminal text in political philosophy and social criticism, presenting an imagined society on an island that explores the concept of communal living and critiques contemporary European societies. "Utopia" introduces the term itself as a reference to an idealized place or state of things, showcasing More's vision of a society based on reason, justice, and communal ownership.

The other works mentioned are significant in their own rights but are attributed to different authors or contexts. "The Faerie Queene" is an epic poem by Edmund Spenser that celebrates the virtues of the Tudor monarchy, while "The Nymph's Reply to the Shepherd" and "The Passionate Shepherd to His Love" are both pastoral poems attributed to Christopher Marlowe and Sir Walter Raleigh, respectively. Hence, More's "Utopia" stands out as his most critical and influential contribution to literature.