•Why it earns a slot
Utopia gave English the word 'utopian' and remains the founding text of the genre, combining a precise critique of Tudor enclosure and judicial cruelty with the first sustained argument in English political thought that common ownership, not private property, is the precondition of justice.
Thomas More frames a dialogue in which the traveller Raphael Hythloday describes the island commonwealth of Utopia, where property is abolished, labour is shared equally, and citizens live in rational plenty under tolerant laws. The first book attacks the social evils of Tudor England, especially enclosure, idle nobility, and the hanging of thieves, while the second book details Utopia's institutions as an implicit rebuke to European governance. More himself remains a sceptical narrator, wishing rather than expecting that Europe might follow Utopia's example.
This distillation is written from the freely available original, which is always the better read when you have the time: gutenberg.org.