The initial list in this post is very partial, and needs to be clarified - hardy in Sparks, Nevada may not translate well to other parts of the world. Dry winters with cold daily minima, but nearly always much warmer daytime temps may be suited to some cacti, but may, for example, kill others with ability to cope with multi-day mild freezes, but less resistance to brief very low overnight temps.
This list misses huge swathes of south american cacti, for example, which have good frost tolerance, such as many Parodias, Gymnocalyciums, Rebutias, Lobivias, etc, and Maihuenias and Austrocacti which may well be far hardier still. Columnars that could make an arbitrary "cold hardy somewhere" list include many Trichocereus a well as Oreocereus and Cleistocactus strausii.
Discuss hardy cacti grown outside all year.