Monday
Monday's claim to heroism remains, by any reasonable metric, profoundly limited. The day itself performs no rescue operations, saves no cats from trees, and has never once carried an unconscious person to safety. Its primary achievement involves existing with such reliability that humanity has built elaborate coping mechanisms around its arrival.
Some argue that Monday demonstrates a form of passive heroism by providing structure to the working week, but this interpretation requires considerable generosity of spirit. The day's most heroic act may simply be ending, typically around midnight, allowing Tuesday to assume its marginally less despised position.