Immortality is the power to possibly live an eternal lifespan.
Users of this ability can not be killed through natural means but can still die or be vanquished through magical means.
This is another ability possessed by whitelighters which they gain after already losing their mortal lives.
The demon Alastair Caine is also immortal, as he was stated to be Around 3000 years old, and maintained the appearance of a middle aged person.
Divine entities, also known as gods, naturally possess immortality.