Longevity refers to long lifespans, usually far longer than human's.
Many beings show extended longevity, usually by virtue of some supernatural trait. This can range from a 300 year average lifespan to near immortality.
Due to their use of magic, the essence of creation itself, wizards can innately heal at the idealized maximum of human potential. For example, when human bones break, there is usually a fracture or flaw left behind after it has healed. With wizards this is not the case, as their bones have almost no detectable trace of any damage after healing. This, when extrapolated to other bodily functions, delays the natural breakdown of the body for a great deal of time before old age finally catches up with the wizard, allowing them to live in excess of 400 years.
Denarians can draw upon the strength of the Fallen Angels bound to their coin; the Fallen's power protects the bearer from the ravages of time, allowing them to survive indefinitely. The loss of the coin causes the Denarian to age rapidly and die a short few years later. In any case, Denarians can be killed accidentally or intentionally.
Scions generally possess extended longevity, if not nigh-immortality, from their immortal parentage. They have been known to live for hundreds of years, although they can be killed.
Changelings possess extended longevity by virtue of their parentage, in this case faerie parentage. Choosing to embrace their faerie nature will turn them into fully fledged faeries, whereas choosing humanity (or refusing to make a choice at all) will nonetheless provide supernatural traits, with some changelings being older than some Winter Queens.
Black Court vampires
Black Court vampires are undead. They are not technically alive as mortals or faeries are, and they do not die of old age; in fact, the older they are, the stronger they become. Despite this, Black Court vampires can be killed by all of the traditional means laid out in Bram Stoker's Dracula.
White Court vampires
White Court vampires derive nigh-immortality from a symbiotic spirit called the Hunger, which is what defines them as vampires. The Hunger feeds off of life essence, in a way defined by the vampire's House, using that essence to sustain itself and its host. So long as the vampire can feed, their Hunger will keep them alive indefinitely, though they can still die by accident or murder.
Red Court vampires
Half vampires are mortals who have received the blood thirst from a Red Court vampire, but have not yet given in and slaked that thirst, transforming into a full vampire. This blood thirst is able to sustain, empower, and heal its host to a partial degree, increasing their longevity by several hundred years or more. However, this spirit is sharply limited in the healing and regeneration it can provide, as it lacks sustenance.
Outsiders, like faeries, cannot be killed. They can be harmed, but they cannot die.
- White Night, ch. 1
- Jim Butcher forum post
- Dead Beat, ch. 4
- Jim Butcher forum post
- Dead Beat, ch. 37
- Cold Days, ch. 1
- Blood Rites, ch. 35
- Summer Knight (novel), ch. 33
- Cold Days, ch. 51
- "It's My Birthday, Too"
- Blood Rites, ch. 6
- Blood Rites, ch. 3
- Blood Rites, ch. 5
- Grave Peril, ch. 18
- Changes, ch. 35
- Changes, ch. 4
- Death Masks, ch. 1
- Changes, ch. 37
- Blood Rites, ch. 42