Even if you aren’t familiar with Marvel’s gun-toting brutal vigilante, the Punisher, chances are you’ve seen his symbol: a leering white skull on a black background.

Showing up in Iraq and Afghanistan on unofficial unit patches; spray-painted on buildings, vehicles, and equipment; and as military tattoos, the skull may have greater renown than the comic-book character, especially among service members.

Pfc. Ronnie Butler, a gunner with Company B, 2nd Battalion, 87th Infantry Regiment, tattooed a tribute to his close friend, Spc. Joshua Farris, on the back of his arm.U.S. Army photo by Sgt. Matthew Thompson

The Punisher, aka Frank Castle, is a former Force Reconnaissance Marine and Vietnam War veteran, though in newer issues his military service has become more nebulous, hinting at the character’s involvement in more recent conflicts. After the death of his family, Castle dons the guise of the Punisher, a pitiless anti-hero who delivers justice to his targets in the form of violent death. Wearing all black with a white skull emblazoned on his chest, the symbol is usually the last thing his targets see.

The Punisher’s skull has appeared all over the place, especially in films about the military, from John Krasinski in “13 Hours: The Secret Soldiers of Benghazi” rocking a skull patch on his flak, to Navy SEAL veteran Marcus Luttrell showing up in “Range 15” with his face painted like the Punisher skull, to its numerous appearances in “American Sniper.”

It’s become so prevalent that a recent Punisher comic-book series included a scene where he rescues a group of U.S. Army Special Forces soldiers who later adopt his symbol as a unit patch when they deploy to Afghanistan.

“I was trying to explain why every special operations guy I know basically has a Punisher patch of some sort, and why every conex and trunk had a Punisher skull painted on it somewhere,” explained Kevin Maurer, who co-wrote “No Easy Day,” with Matt Bissonnette. Maurer also worked on issues #7 and #8 of “The Punisher” series in 2014. “In the Marvel universe, if all these guys had Punisher skulls, why would they have Punisher skulls on their gear?”

The answer for Maurer was to make the character’s military service a more central part of his identity.

The cover of Marvel Comics’ “The Punisher #008.”Marvel Comics' illustration by Mitch Gerads.

“The thing that stuck with me with the Punisher in that story was this idea of brotherhood,” Maurer told Task & Purpose. “What I was trying to get to with the story was to try to show that the Punisher’s world view was colored by his time in the service.”

According to Gerry Conway, one of the character’s original creators, the Punisher’s evolution may be indicative of how the perception of the military has changed.

“The Punisher as a character is a bit of a Rorschach test in that as time has passed since his creation, we’ve gone through different cultural eras and through each of those the character has been reinterpreted to reflect the concerns of society,” said Conway, in reference to the end of the Vietnam War and the way many veterans were treated when they came home.

“If society feels what we are doing is justifiable, the respect for the military is high, if the society feels guilty or shamed in what we’re doing, we project that onto the military,” said Conway. “They are the recipients of our collective Id.”

And this comes out in creative works, like comics.

The Punisher of the Vietnam era was indicative of not only how veterans of that war were sometimes perceived, but how they may have felt toward their country and their government, Conway explained.

“Veterans were being abused when they would come home, they weren’t being greeted with ticker tape parades,” said Conway, who drew a parallel between the stigma faced by some Vietnam War veterans and Punisher’s origin story.

“Someone like the Punisher has already been alienated from society and doesn’t feel like he’s part of society, so when society lets him down when his family is killed he doesn’t feel a tremendous obligation to following the rules,” said Conway.

The perception of the military and how it manifests in pop culture, continues today, with the most recent adaptations of the anti-hero engaged in a war against evil, seemingly without end, but nonetheless committed to the cause.

“He’s like the single Marvel universe operator,” Mitch Gerads, the illustrator for the 2014 series, told Task & Purpose. “The military has a way of going about things and it’s a very tactical mindset, especially special operations. … We just approached it from this tactical mindset … and it’s in a way our homage to the actual warriors we met, and know, and love.”

The Punisher first appeared in 1974 in “The Amazing Spider-Man #129” and since that time has changed dramatically, with his military service looking less like an addendum to the character, and more like an integral part of the Punisher’s identity.

The character will debut on March 18 in season two of the Netflix’s original series, “Daredevil.” He is set in sharp contrast to the show’s protagonist. Daredevil is another Marvel vigilante, who unlike the Punisher, beats criminals to a pulp instead of just shooting them in the face.

The Punisher’s appeal to both the military community and civilians may have as much to do with his background as his approach to problems.

“He takes with him a military code for accountability and responsibility and he is very much an objective oriented person,” said Conway. “There’s not a lot of room for nuance when you’re in a  firefight. … He in that sense has a certain appeal.”

But Conway was also conflicted about what characteristics troops most related to. Was it the character’s relentless drive, or something more sinister like his “no quarters” attitude toward those he deems evil?

“When I first heard about it, I heard about it in the context of it being used by the Iraqi militia who had been trained by U.S. forces and kind of adopted it,” said Conway, referring to the skull’s appearance in Iraq.

“I find it flattering, but also a little unnerving because I never actually felt the Punisher was one of the good guys,” said Conway of the character’s popularity in the military. “I don’t think the Punisher is a hero; he’s an anti-hero. He’s someone that rises up from our subconscious and acts on our behalf and is a symbol really of cultural breakdown.”

Conway explained that the Punisher is “a dark vision of the effect of social breakdown.”

If the Punisher shows up, then something has gone horribly wrong. But in a world of complex and nebulous threats where nothing is simple, the character offers readers a direct solution to incredibly complicated problems.

“There’s something kind of great about the Punisher, something really simple,” said Maurer. “I think his methods are up for scrutiny, but his aim, his goal, the intent of what he’s trying to do —  it’s justice, it’s reciprocity, it’s revenge.”