Created from Peter Parker's DNA by the Jackal, this clone was made to fight him as part of Jackal's torment to Spider-Man, blaming him for Gwen Stacy's death. In the fight, only one could survive in order to save Ned Leeds from a bomb. When the Jackal had an eye-opener and freed Ned, activating the bomb, seemingly dying and killing the Clone. Spider-Man got the corpse and buried him at a industrial chimney, but he was alive and managed to survive due to the Jackal injecting him with something earlier while he was unconscious. In an attempt to sow confusion between Peter Parker and Ben Reilly the Jackal dumped another Spider-Clone down the same smoke stack Peter Parker dumped Ben Reilly in after he rescued Ben.
Then, the clone spent the next five years in exile from New York, believing himself to be a worthless clone. He dubbed himself "Ben Reilly", using his Uncle Ben's first name and his Aunt May's maiden name, Ben Parker and May Reilly respectively.
During this time Ben began working as a janitor in a Portland high school using the alias "Henry Jones", initially allowing himself to be regarded as mentally handicapped until he rescued a woman from home invaders, helping him realize that he could still make a difference. This self-revelation was further aided when he met a friend, Seward Trainer, who inspired him with confidence to be his own person, Trainer also helping Ben by providing him with fake references to find work; Seward's references and Ben's own skills would allow him to work for a month or so at a time until people learn that the credentials are fake and Ben moves on.
Returning to New York when he found out about Aunt May's failing health, Ben came face-to-face with Peter and had to explain his reasons for returning, his presence also inspiring Peter to get through his current dark mood after recent tragedies.
After an initial distrust of each other, Peter and Ben became friends and worked side by side as Spider-Man and the Scarlet Spider, until after some tests by Seward Trainer, it was revealed that Peter was the clone and Ben had been the real Peter Parker. This drove Peter almost insane and left Ben stunned. They agreed to keep their names, since Ben still didn't feel like he deserved the name.
Peter soon gave up the webs when he found out that Mary Jane was pregnant, allowing for Ben to become Spider-Man. Ben enjoyed life as Spider-Man and had his own adventures, working as a waiter at local coffee house the Daily Grind and dating local university students Jessica Carradine (Until it was revealed that she was the daughter of the burglar who killed Uncle Ben) and Desiree Winthrop.
Despite accepting his clone status, Peter retained some suspicions over the results, and began delving into Seward Trainer's past in order to find out if he was to be trusted. Eventually, it was revealed that Trainer was working for Gaunt and Norman Osborn. Norman had survived the glider to his chest all those years ago and created the whole clone saga in order to drive Peter mad.
During a confrontation between the Green Goblin and the two Spider-Men, Norman impaled Ben Reilly with his glider and Peter watched as he seemingly disintegrated away, proving that Ben was the clone all along.
Ghosts of the past
Years later, Peter was attacked by a man named Damon Ryder (using the name Raptor), believing him to be Ben Reilly. Raptor showed Spider-Man a sketch of the arsonist and revealed that the arsonist looked like Peter and Ben.
Ryder then appeared in New York City and confronted Peter, still believing him to be Ben Reilly and repeatedly calling him "Ben". The two fought in the middle of the office of Frontline after Raptor threatened to target Peter's family. Ryder gained the upper hand before Peter's coworkers got in the way, then left after handing over the article on the arsonist, with Ben Urich noting that it appeared to be Peter in the sketch. Ryder ditched his jacket not knowing a spider-tracer was on it, and headed to Peter's apartment to seemingly attack his roommate. When Spider-Man reached the tagged jacket, he was attacked by Kaine. After a scuffle with Kaine, Peter returned to his apartment and found his roommate unharmed, though she gave him the address of Aunt May's home. Peter headed there, only to find Raptor holding Harry Osborn and his cousins hostage at gunpoint. As Raptor announced his plans to burn his friends and family to death right in front of him after he admitted his "true identity" as Ben Reilly, Kaine arrived, revealing that he had been working with Raptor. Kaine exposed both Peter's identity and his status as a "clone" of Reilly to Raptor, encouraging him to kill him, since if Reilly was a murderer, then Peter could be driven to kill as well. Refusing to accept this, Peter beat Raptor unconscious, while affirming his and Reilly's innocence and the fact that they would never murder anyone. He was forced to flee when the police arrived, so Kaine and Raptor escaped.
As a clone of Spider-Man, the Scarlet Spider possessed the same powers he did.
Superhuman Strength: The Scarlet Spider possessed the proportionate strength of a spider, granting him superhuman strength. He was capable of lifting 10 tons or more when under extreme stress. The Scarlet Spider's strength extends into his powerful leg muscles which allows him to leap heights and distances far beyond human capability.
Superhuman Stamina: The Scarlet Spider is able to exert himself at peak capacity for several hours before fatigue begins to impair his performance.
Superhuman Durability: The composition of the Scarlet Spider's skeleton, inter-connected tissues, and nervous system had all been enhanced. His bodily tissues were somewhat more durable and resistant to impact or trauma than an ordinary human, although he was certainly not invulnerable. While his body was tougher than an ordinary human, he could still be injured in ways comparable to an ordinary human. He was seemingly killed when impaled in the back by the Green Goblin's goblin glider. However, if injured, his body is capable of repairing itself somewhat faster than an ordinary human is capable of.
Superhuman Agility: The Scarlet Spider was extraordinarily limber and his tendons and connective tissues were twice as elastic as the average human being's, despite their enhanced strength.
Spider-Sense: The Scarlet Spider possessed an extrasensory "danger" or "spider" sense which warned him of potential immediate danger by the manifestation of a tingling sensation in the back of his skull, and links with his superhuman kinesthetics, which enabled him to evade most any injuries, unless he cognitively overrode his automatic reflexes. The precise nature of this sense is unknown. It appeared to be a simultaneous clairvoyant response to a wide variety of phenomena (everything from falling safes to speeding bullets to thrown punches), which had given several hundredths of a second warning, which was sufficient time for his reflexes to allow him to avoid injury. The sense also could create a general response on the order of several minutes: he could not discern the nature of the threat by the sensation. He could, however, discern the severity of the danger by the strength of his response to it. The Scarlet Spider's spider-sense was directional and could guide him to or away from hidden weapons and enemies. Sudden and extreme threats could cause his spider-sense to react with painful intensity. The Scarlet Spider could also sense and dodge attacks directed randomly or by a computer. Using his spider-sense to time his enhanced reflexes, the Scarlet Spider could casually dodge attacks up to and including automatic-weapons fire, provided there was sufficient distance. His spider-sense was sufficiently well-linked to his reflexes to the point that a threat could trigger them even when the Scarlet Spider was asleep or stunned. His spider-sense had helped him preserve his secret identity since it alerts him to observers or camera when changing into or out of his costume. The spider-sense did react to those who Ben does not consider to be a threat. The Scarlet Spider could choose to ignore his spider-sense, and distraction or fatigue diminished its effectiveness. The Scarlet Spider's fighting style incorporates the advantage that his "spider-sense" provides him. An interesting sidenote was that, because Ben was not the host of the Venom Symbiote and was cloned before the Symbiote was bonded to Peter, his spider-sense did not see the Venom symbiote as himself, and Venom therefore triggered his spider-sense.
Superhuman Reflexes: The Scarlet Spider's reflexes were faster than an average human by about a factor of 15 (he was often able to dodge bullets only inches from hitting him). His practical reaction time was at least a dozen times that of a normal human. In combination with his spider-sense, the speed of his reflexes allowed him to dodge almost any attack, even bullets only inches away from his face.
Superhuman Speed: The Scarlet Spider is capable of running and moving at speeds that are far beyond the natural physical limits of the finest human athlete. Scarlet Spider has showed to be fast enough to catch up to an accelerating car while on foot, but prefers to travel by webs.
Superhuman Equilibrium: The Scarlet Spider possessed the ability to achieve a state of perfect equilibrium in any position imaginable. He seemed able to adjust his position by instinct, which enabled him to balance himself on virtually any object, no matter how small or narrow. He had developed a unique fighting style that made full use of his agility, strength, and equilibrium.
Wall-Crawling: The Scarlet Spider possessed the ability to mentally control the flux of inter-atomic attraction (electrostatic force) between molecular boundary layers. This overcame the outer electron shell's normal behavior of mutual repulsion with other outer electron shells and permitted the tremendous potential for electron attraction to prevail. The mentally controlled sub-atomic particle responsible for this has yet to be identified. This ability to affect the attraction between surfaces was so far limited to the Scarlet Spider's body (especially concentrated in his hands and feet) and another object, with an upper limit of several tons per finger. Limits to this ability seemed to be psychosomatic, and the full nature of this ability has yet to be established.
Scarlet Spider received a few new powers, when he bonded with Carnage symbiote. Mostly, he didn't use these powers.
Enhanced Superhuman Strength: Originally able to lift 10 tons, after merged with symbiote, he could now lift about 80 tons.
Camouflage Capabilities: The symbiote possessed limited shape-shifting abilities in the sense that it was able to immediately change itself to appear as any type of clothing or garment.
Constituent Matter Generation: Ben was able to generate tentacle-like appendages from various parts of his body.
Constituent-Matter Manipulation: With symbiote, Ben was able to morph sections of his body, such as his hands or feet, into bladed weaponry such as spikes, blades, or axes. He could also detach these bladed weaponry if he choosed to.
Webshooters: Ben originally had webshooters the were duplicates of Peter's. After his first encounter with Venom Ben redesigned his webshooters. Ben's webshooters were redesigned to use twisting wrist motions as opposed to Peter's double tap. He also added the following to his arsenal:
Impact Webbing; Web pellets that upon impact (hence the name) release tendrils the ensnare the target.
Stingers; Metal darts with a paralitic element that is used to temporarily incapacitate foes.
For a short time, the Carnage symbiote merged with Ben, creating the creature, Spider-Carnage.
Ben dyes his hair blond, to lessen his resemblance to Peter Parker.
Ben, like all of Peter's clones, does not set off Peter's Spider-Sense and vice versa.
Venom is not hidden from Ben's Spider-Sense as the symbiote was never bonded to Ben.
A new Scarlet Spider series began in 2012, but Ben is not the main character. His fellow clone Kaine is the main character.
Ben's "death" was written purposely ambiguous as it was established that only fresh clones would melt or disintegrate upon death. To this point however, Ben has not been brought back in the 616 continuity, leaving this plot hole open ended.