Gentry was a U.S. government weapons designer who invented an armored battlesuit coated in sharp, protective quills and outfitted with a host of concealed miniature weapons. Convinced that the government would give him virtually no credit or reward for his brilliant designs, Gentry kept the suit to himself and decided to use it for personal gain as a costumed criminal called the Porcupine, convinced that he would become the greatest super-criminal the world has ever known.

His first target was a bank vault touted as impenetrable. Although Porcupine succeeded in breaking in and escaping the authorities, he caught the attention of the original Ant-Man (Hank Pym), who tracked him down with his partner, the Wasp, and defeated him, forcing him to escape. Soon after, the Porcupine sought revenge against Pym (in his new guise as Giant-Man) by infiltrating Giant-Man’s fan club to get close to him. After a long battle, Porcupine got the upper hand by seizing one of Giant-Man’s size-altering capsules. Unfortunately, Porcupine grabbed a shrinking capsule and shrunk out of sight.

The effects of the gas soon wore off, and he was recruited by Doctor Doom to disrupt the wedding of the Fantastic Four. Thereafter, the Porcupine continued to pursue a long, undistinguished criminal career, always as a member of some team. He was first recruited by Count Nefaria that brought him into conflict with the X-Men, and later a member of Batroc’s Brigade and an agent of the Cowled Commander, both time fighting against Captain America. More defeats followed against the Defenders, Iron Man, the original Yellowjacket (Pym in yet another costumed identity), the Wasp, Nighthawk and Nomad.

Eventually, however, Gentry grew weary of his unsuccessful criminal career and decided to sell his suit to the highest bidder so that he could retire comfortably. Unfortunately, the Porcupine had long since developed a reputation as a loser. As a result, most criminals and criminal organizations had no interest in the Porcupine armor, and the few offers Gentry did receive were insultingly low. Desperate, Gentry took the unusual approach of offering to sell his battlesuit to the Avengers for a fair price, arguing that this would prevent the suit from falling into criminal hands. Captain America, intrigued by Gentry’s offer, agreed on the condition that Gentry assist him in a sting operation aimed at capturing members of the criminal Serpent Society. Gentry reluctantly accepted the terms, but was fatally wounded in the process of helping Captain America capture several Society members. Captain America tried to console the dying Gentry by praising him for assisting in the capture of dangerous criminals, and he assured Gentry that he was a worthy opponent, but the despairing Porcupine insisted with his dying breath that he was an insignificant loser.

After Gentry’s death, Captain America had the Porcupine battlesuit displayed in Avengers Mansion, labeled "Battle Armor of the Porcupine—Honored Foe of the Avengers". The villain Mister Hyde smashed the Porcupine display when he and the Masters of Evil invaded Mansion, but the display has since been reconstructed when the Mansion itself was restored by Ute the Watcher.