Healing Factor is the innate power to heal the user's body from physical injuries at a faster rate than that of humans' healing processes.
This power is commonly associated vampires, werewolves, witches, warlocks, shape-shifters, and chameleons.
Overview
It appears that most supernatural species possess this power, with varying degrees of potency.
If the inflicted dies, the healing factor will cease to work as the body is no longer functional. It also appears that the healing process slows down with age.
Werewolves
For werewolves, the speed of healing depends on how close the full moon is.
Vampires
Vampires need to consume blood to speed up the healing process but are ultimately fast healers.
When Anthony Bastin was stabbed and left to die, his accelerated healing and physical strength were severely depleted. Miranda and Tabitha each gave him some of their blood, which helped speed up his healing process, allowing him to recover just enough to run.
Witches and warlocks
Witches and warlocks are said to be fast healers as well, though it takes weeks to heal severe injuries.
Miranda Kane was severely injured in an explosion that ended with her arm put in a cast. She insists witches heal fast too when she decides she no longer wants to sit around.
Shape-shifters
Shape-shifters quickly recover from even the deadliest of injuries when they shift from animal back to human form, but can still feel the pain.
Perry Gomez came close to dying when he broke his neck in bird form but was able to shift back to human form before he succumbed to his injuries.