Fictional city-states
Tyrosh (A Song of Ice and Fire book series)
Ville-France, an utopian French-speaking city-state in Jules Verne's The Begum's Fortune
Volantis (A Song of Ice and Fire book series)
Waterdeep (Forgotten Realms, a Dungeons & Dragons campaign)
Xanne-Sandansky(Phillip Reeve's Mortal Engines series)
Ys (from Roger Zelazny's Traveller in Black)
Zaun (League of Legends video game)
Zero One (The Matrix series of films)
Zion (The Matrix series of films)