True immortality, as in actual immortality that makes it unnecessary to eat, possibly sleep, and unable to die in general. Not like vampires (sorry, needed to insert that one) or classical immortals that just don't die of age or wounds. I personally distinguish the two as otherworldly immortals and humane immortals.
And add to that something that would actualy be practical in day-to-day situations and make life actually easier, such as ability to shapeshift (which could actually be the cause of immortality) or superior mental and physical capabilities.
...Actually wait, does that count as a superpower? It should. I think