dnd 5th – Who are the official PC mechanics who directly fight death?

For example, the subclass Path of the Barbarian Zealot at the 14th level receives the Rage Beyond Death feature (XGtE, p.11), which prevents you from dying during rabies:

From the 14th level, the divine power that fuels your rage allows you to not suffer fatal blows.

When you are unleashed, having 0 points of life does not make you unconscious. You must still perform lifejackets, and you suffer the normal effects of taking damage at 0 health. However, if you die because your saving throws of death fail, you will not die before the end of your rage and you will die only if you still have 0 life.

What other mechanisms are available to players that can either postpone or cancel death?