This special issue of the Journal of Online Trust and Safety, guest edited by Ronald E. Robertson, brings together research on Uncommon Yet Consequential Online Harms, including: a paper sampling YouTube users skeptical of the 2020 U.S. election's legitimacy, finding that the platform was more likely to recommend them videos about the legitimacy of the election; a paper surveying self-identified incels to expand our knowledge of support for illegal or violent political action among them; a paper surveying rule violators on Twitter, finding that those who felt more fairly treated during Twitter's enforcement were less likely to violate the rules again; and a paper on an experiment involving U.S. participants, finding that adding disputed tags to headlines reduced sharing of misinformation among Democrats and Independents, but not Republicans.