Hard to Be a God

On a medieval alien world where progress has stalled under tyranny and superstition, the Earth historian Anton lives undercover as the nobleman Don Rumata, forbidden from interfering no matter how much cruelty he witnesses. As the kingdom of Arkanar descends further into purges and violence, Rumata's careful neutrality becomes impossible to sustain. One of the Strugatsky brothers' most acclaimed novels, and a foundational Noon Universe text.