Ottoman Empire
Muslim sects regarded as heretical, such as the Druze, Ismailis, Alevis, and Alawites, ranked below Jews and Christians. In 1514, Sultan Selim I, nicknamed "the Grim" because of his cruelty, ordered the massacre of 40,000 Anatolian Alevis (Qizilbash), whom he considered heretics, reportedly proclaiming that "the killing of one Alevi had as much otherworldly reward as killing 70 Christians."[page needed] Selim was also responsible for an unprecedented and rapid expansion of the Ottoman Empire into the Middle East, especially through his conquest of the entire Mamluk Sultanate of Egypt, which included much of the region. With these conquests, Selim further solidified the Ottoman claim for being an Islamic caliphate, although Ottoman sultans had been claiming the title of caliph since the 14th century starting with Murad I (reigned 1362 to 1389). The caliphate would remain held by Ottoman sultans for the rest of the office's duration, which ended with its abolition on 3 March 1924 by the Grand National Assembly of Turkey and the exile of the last caliph, Abdülmecid II, to France.

Q: What group did Sultan Selim I consider heretics and subsequently slaughter?
Anatolian Alevis (Qizilbash)