Films to which Roger Ebert gave no stars at all, only a 🚫 or a 👎. He was sparing with this rating, only giving it to movies that offended him on a moral level. (Except in the case of Fathom, which contained nothing more reprehensible than Raquel Welch's acting. But that was very early in his reviewing career.)
In the cases of Pink Flamingos and the first Centipede movie, he refused to give them any rating at all.
There are three other movies on the site that are listed as zero-starred (Lumiere, Tempest, and Erendira), but Lumiere and Erendira were actually three stars, and I'm almost sure that Tempest wasn't zero-starred either. So I've left them out.
Update, 12/01/25: Apparently, "Rosencrantz & Guildenstern Are Dead", "Murder at 1600", "Key Exchange", "Survive!", "Fathom", and "The Master Gunfighter" don't belong here either. Darn you, RogerEbert.com!