The Dragon Masters

On the rocky planet Aerlith, humans have managed to gain a spotty foothold. They live in the valleys with fertile soil and fight occasional battles for territory and general dominance. Said battles prominently involve the semi-intelligent 'dragons', who are specialized for particular combative functions through breeding programs that have been conducted since time immemorial. At regular intervals, a spaceship with aliens, called 'grephs', appears, abducts humans with impunity because of their superior technology, and takes them away breed their own warriors who fulfill a similar function to the dragons. The time for the next greph visit is nigh, and Joaz Banbeck is about to marshal his colorful array of vicious dragons; not only to fight his rival from a neighboring valley, Ervis Carcolo, but also to face down the grephs and show them a thing or two. Why it's at this place on the list: It's only this far down on the list because it's a novella. But it's a tight story that not only rattles a lot of 'social' cages, but also tackles a whole bunch of moral questions and races along at breakneck pace. The irony of the two-sided slave-warrior breeding programmes on both sides of the conflict (the dragons are custom-bred descendants of a few captured grephs from previous invasions) is supreme. The story is proof, if it were needed, that a good writer doesn't need a tome to tell an involving tale. Hugo for best short story in 1963. Read if you like: Jack Vance, or if you need an introduction to his work, depth, enchanting use of language and mordant commentary on human nature and society.