This book considers the enduring legacy of early Muslims who were hostile to ʿAlī and his descendants, the ʿAlids. Later Muslim authors acknowledged the existence of such figures associated with "anti-ʿAlid sentiment" (naṡb) up to the ninth century. Later representatives of both Sunnī and Shīʿī orthodoxy condemned anti-ʿAlid sentiment as heretical, but many of these anti-ʿAlids nonetheless became revered figures in Sunnī Islam. They made literary contributions that subsequent Sunnī authorities transmitted, and circulated views about ʿAlī that later Sunnīs partially accepted as accurate. This book identifies those anti-ʿAlids and the ways in which their beliefs have impacted Sunnī Islam.Anti-ʿAlid sentiment has received little scholarly attention for a number of reasons. First, unlike pro-ʿAlid sentiment, which found intellectual backing in Shīʿism, anti-ʿAlid sentiment in its most radical form was not represented by a parallel independent and enduring sect. Radical anti-ʿAlids participated in a variety of ideological and political circles, but it seems that the sects that flourished did not fully embrace their doctrines. Sunnīs adopted only the more moderate beliefs espoused by anti-ʿAlids active in pro-Umayyad and ʿUthmānī circles. The same can be said about Ibāḋism, the sole surviving branch of the Khārijī community that once encompassed numerous rival factions. The Ibāḋīs denounced other, now extinct Khārijī sects as extremists and hence did not preserve the literary works of their rivals. Although Ibāḋīs today mildly condemn ʿAlī and reject any veneration of him, Khārijī anti-ʿAlidism was much more pronounced in previous centuries. Consequently, heresiographers writing in later centuries did not dedicate separate chapters to anti-ʿAlids.