Which work is William Thackeray best known for?

William Thackeray is best known for "Vanity Fair: A Novel Without a Hero," a satirical novel published in the 1840s. This work is recognized for its rich character development and its critical portrayal of early 19th-century British society, particularly focusing on themes of greed, social climbing, and moral ambiguity. The novel's title references its exploration of vanity and the superficiality of social relationships, making it a significant contribution to Victorian literature. Thackeray's use of a distinctive narrative voice and irony allows for a complex critique of the era's social norms, elevating "Vanity Fair" to a place of prominence among literary classics.

In contrast, the other works listed—such as "War and Peace" by Leo Tolstoy, "Walden" by Henry David Thoreau, and "Fathers and Sons" by Ivan Turgenev—are notable yet belong to different authors and literary movements. Each of these works addresses different themes and contexts, which helps to clarify why Thackeray’s "Vanity Fair" stands out as his most recognized contribution to literature.