Ultra marathons

According to Wikipedia (link below), “an ultra marathon is basically any foot race longer than a standard marathon” (42.2 kilometres or 26.2 miles).   The four most common ultra marathons are 50k, 50 miles, 100k and 100 miles, basically in that order of popularity.

In addition to distance-related ultra marathons, there are numerous time-based races e.g. 6 hour, 12 hour, 24 hour races up through multi-day races.

Official ultra marathon definition