The character was originally created as a weapons designer for the United States Army, conceived the idea of designing a battlesuit in imitation of a porcupine: it would be covered with quill-like projections for defense. Moreover, it would be able to shoot its quills, or gases, chemicals, or weapons from quill-like tubes, at an opponent. (In actuality, a porcupine cannot shoot its quills, although they can be detached from its body) Gentry spent months working on overtime to create his porcupine battlesuit. He was enormously proud of his achievement when the suit was finished, and believed his invention was worth a fortune. Yet Gentry also believed that the government would pay him, one of its employees, virtually nothing for his creation. Angrily, Gentry decided to keep the porcupine battlesuit and to use it to make himself wealthy through crime. Thus Gentry became the Porcupine, one of the first costumed criminals of his generation.
Hank Pym, who was then the original Ant-Man, and his partner, Janet van Dyne, the Wasp, soon defeated the Porcupine. However, the Porcupine succeeded in escaping, and unsuccessfully tried to take revenge on them after Pym had also assumed the superhuman powers and identity of Giant-Man. During a battle with Giant-Man, the Porcupine stole and consumed a large number of what he thought were the capsules that Giant-Man used to grow in size. In fact, though, they were the capsules Giant-Man used to shrink himself, and the Porcupine shrank out of sight.
Eventually, however, the capsules' effect wore off, and the Porcupine, again at his normal size, was among the many costumed menaces assembled by Doctor Doom to disrupt the wedding of Reed Richards and Susan Storm.
His self-confidence still shaken by his failures in battling Giant-Man and the Wasp, the Porcupine eagerly accepted the invitation of Count Nefaria, a powerful figure in the criminal Maggia, to join his group of costumed agents. Among Nefaria's agents were the original Eel, the Plantman, and the Scarecrow, with all of whom the Porcupine would ally himself in the future as well. The Porcupine and the other costumed agents aided Count Nefaria in his attempt to hold much of Washington D.C. for ransom. However, the original X-Men thwarted Nefaria and his agents. Once again, the Porcupine succeeded in escaping being taken prisoner, and he blamed the failure of the blackmail scheme on Nefaria and the other agents. But Gentry suspected that in fact, he himself was inadequate for the role of being a "super-villain" battling superhuman opponents.
It is not known what the Porcupine did between the end of this venture and his enlistment as a member of Batroc's Brigade. As a Brigade member, the Porcupine unsuccessfully battled Captain America. Months later, the Porcupine and his allies the original Eel, the Plantman, and the Scarecrow, went to work for the masked criminal mastermind who called himself the Cowled Commander. Once again, the Porcupine clashed with Captain America but was defeated.
Convinced that they were failures, Gentry and Leopold Stryke, who was the original Eel, sought guidance from the Celestial Mind Control movement, which was secretly masterminded by the alien Nebulon. Nebulon pitted the Porcupine and the Eel against his foes, the costumed adventurers called the Defenders, who defeated them both.
Later, the Porcupine and a small group of confederates invaded a major Manhattan hotel to steal the valuables in its safe. This time the Porcupine erred by deciding to rob the wealthy attendees at a fashion show in one of the hotel's ballrooms. Unfortunately for him, the show as being given by fashion designer Janet van Dyne, who was also the Wasp. Moreover, Henry Pym, who now used the costumed identity of Yellowjacket, was also present, as was Kyle Richmond, the adventurer called Nighthawk. The Wasp, Yellowjacket, and Nighthawk quickly defeated the criminals, and the Porcupine felt humiliated at being overpowered by the Wasp and Yellowjacket when they were both at the size of insects.
Perhaps believing there was safety in numbers, the Porcupine next turned up as one of a large assemblage of costumed criminals organized by the original versions of Libra and Sagittarius of the android Zodiac. This time the Porcupine was defeated by the Hellcat during a battle between a number of the criminals and a group of adventurers operating under the auspices of the Defenders.
The Porcupine went to prison but was soon released by minions of billionaire Justin Hammer. The Porcupine agreed to provide Hammer with half the proceeds from his criminal activities in exchange for Hammer's financial support. The Porcupine was among the small army of costumed criminals whom Hammer sent to attack Iron Man when the latter turned up on Hammer's enormous "houseboat" headquarters. Iron Man succeeded in defeating all of these criminals. Presumably the Porcupine's failure in this instance was one of the reasons that Hammer fired the Porcupine from his employ.
Tired of his long string of defeats, Gentry believed his criminal career had become a joke. He decided to give up his career as a costumed criminal and live off the millions of dollars he expected to receive by selling his battlesuit. Gentry totally redesigned his porcupine battlesuit, making it far deadlier than before. He entered into negotiations with the subversive organization called the Secret Empire to sell them the suit. The Empire requested proof of the battlesuit's capabilities, so Gentry said he would prove it was the perfect combat suit by testing it in battle against Captain America, the ultimate soldier. But Captain America and his ally Nomad defeated the Porcupine, and Gentry was returned to jail.
In prison, Gentry vowed never to be defeated again, and to ensure that, he decided never to put on the Porcupine battlesuit again. Gentry was soon released from prison, apparently legally, under unknown circumstances, and he set about once more to try to sell the battlesuit. But by now Porcupine was seemingly universally regarded by major criminals and leading subversive organizations as a laughable failure, and hence they saw his battlesuit as virtually worthless to them. Gentry tried to sell it to the Secret Empire, AIM, HYDRA, the Kingpin, the Maggia, the Tinkerer, various others, and finally to the Serpent Society, but almost no one wanted it, and the few offers he did receive for it were insultingly low.
Gentry was in despair, but finally came up with the idea of selling the battlesuit to the Avengers to prevent it from falling into the hands of their enemies. Captain America was intrigued by Gentry's proposal, and in talking to Gentry, learned that he knew how to contact the Serpent Society, whom Captain America had been trying to bring to justice. Captain America agreed to have the Avengers buy the battlesuit if Gentry helped get him to members of the Serpent Society. Gentry accepted Captain America's terms.
Captain America's plan was for Gentry to pretend to have captured him and to offer the Serpent Society the opportunity to kill him. Gentry contacted the Society's leader, Sidewinder, and arranged to have some of the Society Members meet him at a lower Manhattan construction site. Gentry, having reluctantly donned his Porcupine costume once more as part of the plan, pretended to guard Captain America, who was seemingly bound with chains. Gentry was frightened and did not want to have to do any fighting, but Captain America told him he could leave as soon as he had turned the Captain over to the Society members.
Four Society members soon appeared: Cottonmouth, Death Adder, Diamondback, and the Rattler. Captain America took the Society members by surprise, and the Porcupine began to flee. Diamondback, realizing that the Porcupine had set them up, went after him and threw two nitroglycerin-filled diamond weapons at him. The weapons exploded on impact, damaging his battlesuit somewhat, but not harming him. Nevertheless, seeing his only valuable asset, the costume, damaged, Gentry flew into a rage and attacked Diamondback. She again damaged his suit somehow, and as he tried to escape her, he tripped and fell.
Due to the damage to his suit Gentry was impaled on one of his own quills when he fell. Apparently, the quill went into his heart, for the injury proved fatal. Diamondback escaped, but Captain America defeated the other three Society members. Captain America found Gentry dying and in despair. Gentry said that "I'm going to die as I lived…one big loser." Captain America tried to reassure Gentry, told him he had helped him defeat three Serpent Society members, and that therefore Gentry was a hero. But Gentry refused to believe the Captain's kind words, saying that he, Gentry, was "nothing" and had led a worthless life. Captain America replied that Gentry had proved to be a worthy opponent, but it is not known whether this compliment mattered to Gentry, for he expired seconds later without having said another word.
In tribute to Gentry, Captain America had him buried in a grave reserved by the Avengers for those who have fallen in battle, and put his battlesuit on exhibit in Avengers Mansion, labeled "Battle Armor of the Porcupine — Honored Foe of the Avengers".