Aleksei Sytsevich was just another thug in the Russian Mafia, grasping at dreams of easy money, and headed for a short brutal life. Seduced by promises of wealth and power, Aleksei underwent a life-threatening series of chemical and radiation treatments to transform him after several months into the superhumanly strong agent for a collective of professional spies - in part, to support his family. Aleksei's powerful armor permanently bonded to his form, was modeled after the hide of a rhinoceros. Two scientists named Igor and Georgi chose this form, both for its visual impact and in recognition of the fact that the rhino is the result of countless generations of evolution towards the ultimate form for armored assault. They selected Aleksei for his muscular physique and low intelligence, which they believed would insure his loyalty.
Given the code-name Rhino, his first mission was to kidnap astronaut John Jameson, son of Daily Bugle publisher J. Jonah Jameson, and sell him to the highest bidder. He received intensive sub-hypnotic training in American English and false citizenship papers bearing the name Alex O'Hirn. Feeling cocky, he turned on his benefactors, destroying their headquarters, and attempted to abduct Jameson under his own initiative. As the Rhino made his way towards New York City, Spider-Man began to formulate how to defeat this apparently unstoppable foe. His discovered two key factors: once charging, the Rhino cannot change directions or easily halt his advance. Second, Aleksei is rather dumb. Spider-Man deduced that if he could avoid a direct hit from the Rhino's horn, his superior tactical skills and agility would always leave him the final victor in any fair fight.
Spider-Man defeated the Rhino sending the villain to a special state correctional hospital where he was kept under heavy sedation. After a few weeks, the Rhino broke out of the hospital and escaped, seeking revenge of Spider-Man. This time, Spider-Man defeated him using a specially-formulated version of his web fluid, devised with the aid of Dr. Curt Connors, that contained encapsulated acid pellets whose containers dissolved upon contact with air. The special webbing rendered the Rhino's costume weak and brittle, which deprived him of needed impact resistance. The Rhino was recaptured, tried, and convicted. The Rhino served a commuted sentence and was discharged. When he was released, the spies who had transformed him, apparently showing no sign of malice towards his betrayal, approached him with the offer to strengthen him using a gamma-ray process. They had also devised an improved, acid-resistant material rhinoceros suit. Having no other prospects of gainful employment, the Rhino accepted the offer. The new series of radiation treatments were successful and doubled the Rhino's previous strength level. The augmented Rhino's first mission was to abduct Dr. Bruce Banner, an authority on biochemical gamma-ray experimentation, also known as the Hulk. The spies planned to coerce Banner into developing an army of gamma-ray treated superhuman assassins. When the Rhino tried to abduct Banner, Banner transformed into the Hulk and overpowered the Rhino. Again, Rhino was sent to a state facility under heavy sedation and high security.
The Rhino's battle with the Hulk came to the attention of the Leader, one of the Hulk's foremost enemies, who decided that further gamma-ray treatments would give the Rhino enough power to overcome the Hulk. The Leader freed the Rhino from the state facility, and further increased his strength by gamma-ray bombardments. The Leader then dispatched the Rhino to crash the wedding of Bruce Banner and Betty Ross. Succeeding in interrupting the wedding, the Rhino engaged in battle with the Hulk when the Leader accidentally shot him with a radiation blast intended for the Hulk. The Rhino turned on the Leader and caused the Leader's escape module to explode. (Banner's wedding to Ross was subsequently delayed for several years.) The Rhino was left comatose but otherwise unharmed and taken to a state hospital. The Leader used his mental energies to revive him, and reoutfitted him to battle the Hulk once again - this time with the Leader's mind controlling his every move. When the Leader released the Rhino, Aleksei was aboard a space shuttle battling the Hulk. The fight continued until the shuttle crash landed on the High Evolutionary's artificial planet on the opposite side of the sun called Counter-Earth. While the ship automatically repaired its damage, the Leader telemetrically signaled for it to return. The Hulk fought his way back on, the Rhino in tow. When the ship crash landed back on Earth, the Rhino lay buried in the wreckage for some time until he revived.
The Rhino was then recruited by Egghead, as part of the criminal scientist's Emissaries of Evil. The Rhino was paired off with Solarr and sent to Dr. Strange's sanctum to fetch the Star of Capistan, a jewel of power that Egghead mistakenly thought Strange had. The mission brought the Rhino in conflict with his old nemesis, the Hulk, as well as the Defenders. The Rhino was ultimately defeated by the Red Rajah, a being in possession of Dr. Strange. He later battled and was defeated by Doc Samson, and subsequently taken for study to Project: PEGASUS, an enormous energy research facility in upstate, New York. After months of observations, the Rhino joined in a mass escape attempt along with fellow prisoners Moonstone, Blackout, andElectro. The escape was thwarted by the Avengers. While being transferred to another facility, the Rhino was freed by the Miracle Man who wanted the Rhino to help him regain his mystical powers. The Rhino did not wish to be freed, however, preferring to seek medical treatment to remove his costume which had affixed itself to his skin following he fiery shuttle crash. With the aid of the Thing, the Rhino opposed the Miracle Man, and accompanied the Thing back to PEGASUS where they again attempted to transfer him to the medical facility as arranged.
The Rhino was hired by the Green Goblin (Harry Osborn) hoping to earn cash to return to his homeland and convince his family to return back to America with him. Hired to scare Peter Parker, the Rhino was severely beaten by a furious Spider-Man. The Rhino's family was disgusted to learn the means Aleksei was using to gather funds.
When the treatments failed to restore him to normal, the Rhino escaped and joined the Beetle's Sinister Syndicate to earn money to finance further operations. With teammates Speed Demon, Hydro-Man, and Boomerang, the Syndicate nearly overpowered Spider-Man until the timely rescue of the then-reformed Sandman working for Silver Sable.
The Syndicate reunited again, though soon fell apart due to the machinations of Leila Davis seeking revenge against the Beetle, whom she held partly responsible for the death of her husband, the Ringer. Rhino hoped again to use earnings in the Syndicate to remove his suit. The team fell apart and the Rhino, working for the Kingpin, was double-crossed. Rhino, overhearing the scientists who were instructed not to take remove the suit, kidnapped one of the scientist's children, and had his suit finally removed. The Kingpin, not one to be outdone, sent a fake-explosive package to the now more vulnerable Aleksei, letting him know he could always kill him if need be. Rhino, missing the excitement in life, requested Justin Hammer to make him a new removable suit.
Rhino later found himself broke and alone during the holiday season. He stole a Santa Claus costume and made people "give" him money. He agreed to be a mall Santa, but became volatile when the kids did not get along with him. The Hulk was there, and a fight ensued in which the Rhino gored the Hulk. However, with a little girl crying, the Rhino spent the next few hours at the mall as Santa on much better behavior.
The Rhino even joined a minor league baseball team, wearing a suit of "Mecha-Rhino" armor, resulting in two clashes with the Hulk.
In the Great Game, a gambling operation run by a group of wealthy individuals who wager on the outcome of battles between their sponsored super-powered contestants, sponsor James Johnsmeyer sent the Rhino to pressure the deformed Spider-Man clone, Kaine, into becoming a contestant. Joystick and Polestar joined the fight while the sponsors wagered on who would draw first blood. Double points were offered for Spider-Man as a wildcard while he tried to defend Kaine. Uninterested in joining the Game, Kaine seriously battered the Rhino while Spider-Man tackled Polestar and Joystick.
In another scientific experiment, the Rhino attempted to enhance his limited intelligence. The experiment was too successful, rendering him too smart for his own good. His new intellect ruined a romance, and he became suicidal. However, instead of giving up on life, he reversed the procedure and returned back to his former IQ.
The Rhino battled Hammerhead's gang but was taken down again by Spider-Man. In Canada, the Rhino became subject to experimentation whereupon he was mutated into a half-man / half-rhino creature temporarily. The Juggernaut, attempting to reform his life, stopped the bestial Rhino, rejecting an opportunity to escape his own sentencing. The Rhino was reverted back to his previous superpowered self, whereupon he abducting and proposed to a French female singer/songwriter. Subsequently, after Spider-Man apprehended him, he was jailed in a special section of Ryker's Island prison for superpowered criminals at the same time as the Green Goblin (Norman Osborn). The Rhino was seen free from jail, whereupon Colleen Wing knocked down and apprehended him after she crashed Misty Knight's Jaguar XK8 straight into him. After Spider-Man publicly revealed his secret identity, the Rhino was enlisted in the Chameleon's Exterminators team, and defeated Spider-Man. However, after the Chameleon's arrest, the Rhino was left unpaid, and went on a drunken rampage. However, the Black Cat convinced the Rhino to end his tirade while Spider-Man recovered.