Besides those already mentioned, there are some other meanings of the skulls tattoos that have their roots in some ancient beliefs and practices.
Skulls as trophies - it was a common practice to keep the skulls of the killed enemies and to display them as trophies (eg.: to decorate with them the city walls and towers, to keep the skulls on the palisades as a warning sign, to display them on pikes at the Traitor's Gate, etc) or even to use them as wine-cups. Skulls-tattoos as trophies are a very common theme when it comes to the gang tattoos, prison tattoos, etc. For example, if we consider the russian criminal tattoos, a skull tattoo signifies murder (a significant one). When a tattoo design combines skulls with military insignia (especially with the epaulets tattooed on the shoulders), it usually designates a murderer.
The epaulets are distinctive decorations for the inmates who are members of the "Vory V Zakone" (aprox "Thieves in law"). An inmate who has this kind of tattoo is a person with a high position in the prison hierarchy. The presence of the skull designates the wearer as a murderer. Read more about this topic on this blog: russiancriminaltattoo.blogspot.com
A russian criminal tattoo. The presence of the epaulets indicates that the wearer has a high rank in the prison hierarchy. The presence of the skull designates the wearer as a murderer. The spider is a symbol with multiple meanings; it may symbolize racism, doing time in prison, drug addicted, etc. Read more about this topic on this blog: russiancriminaltattoo.blogspot.com
In the Mexican tattoo-culture, skulls and skeletons are linked with the celebration of the Day of the Dead. The most common themes and representations are: the sugar-skull (brightly colored and highly decorated), the partying skeletons (because El Dia de los Muertos is not a time for sadness, but for joy and celebration) and the in-loving-memory-tattoos (these tattoos include attributes of the passed person in the skull's design: her favourite flowers, his / her weaopns, facial features, etc).
In-loving-memory-tattoo. Some of the passed person's features are still present (the moustache and the hair)
Typical Mexican tattoo: a fancy dressed skeleton playing a violin
For the Mexicans, El Dia de los Muertos is not a mournful day, but a day of family gatherings and holiday cheer.
Alchemy and Magic - the skull is an ancient symbol and it has several embodiments of the alchemical “union of opposites”, an ancient doctrine which accepts a syncretism of conflicting views, a harmony as opposed to a never-ending conflict between Good and Evil.
Wisdom - sometimes, a skull tattoo is a symbol of the mature realization of a continuity of life into death, and the ability to accept death. This is very important because it is only when a person can live with the presence of death that he can fully learn to appreciate life.
Related posts:
Various elements which can occur in a Death tattoo: skulls and skeletons (1)
Skulls and skeletons tattoos (2)
Death tattoo - various elements which can occur in a Death tattoo
Death tattoos: the main depictions of the Grim Reaper
Death Tattoos / Grim Reaper Tattoos: themes and meanings
Death tattoo - various elements which can occur in a Death tattoo - animals