A lone wolf is an animal or person that generally lives or spends time alone instead of with a group. The term originates from wolf behaviour. Normally a pack animal, wolves that have left or been excluded from their pack are described as lone wolves.
As an animal, a lone wolf is a wolf that lives independently rather than with others as a member of a pack.
In the animal kingdom, lone wolves are typically older wolves driven from the pack, perhaps by the breeding male, or young adults in search of new territory. Many young wolves between the ages of one to four years old leave their family to search for a pack of their own. This has the effect of preventing inbreeding as there is typically only one breeding pair in a wolf pack. Some wolves will simply remain lone wolves; as such, these lone wolves may be stronger, more aggressive and far more dangerous than the average wolf that is a member of a pack. However, lone wolves have difficulty hunting, as wolves' favorite prey, large ungulates, are onerous for a single wolf to bring down alone. Instead, lone wolves will generally hunt smaller animals and scavenge carrion.
As a person, a lone wolf is an individual who prefers solitude, is introverted, or who works alone.
In literature, lone wolves are aloof and emotionally unable or unwilling to directly interact with other characters in the story. A stereotypical lone wolf will be dark or serious in personality; they are often taciturn and distinguished by their reserved nature.
A similar concept is the lone wolf of a particular group, who spends enough time with a group to be considered a member but not enough time to be very close to the other members. Such people tend to not take part in the group activities or "get-togethers". Part of this concept arises from the fact that the lone wolf has been pushed away from the group but still has a very strong bond to the "pack". He or she will use the traits of the former pack to find and develop a new one if possible. This may involve establishing mating dominance of a certain member of another pack. This refreshes the idea that this behavior is suggestive of rejected inbreeding within a social system.