•Why it earns a slot
Why it earns a slot: it is subtitled A Novel without a Hero and means it, running an anti-heroine through decades of English society without a single reliable moral center to root for.
A penniless schemer claws her way through English high society while her sweet, passive best friend gets used by everyone around her, and Thackeray refuses to give either of them a hero to marry.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.