The daughter of a restaurant and hotel owner, Liz Allan came from a family of privilege. She and Peter Parker were childhood friends, but once in high school she became part of the "popular crowd" (along with boyfriend Flash Thompson and buddies Jason Ionello, Sean "Tiny" McKeever, Seymour O'Reilly, and Sally Avril) who were often picking on him. However, when everyone thought that Peter was foolishly impersonating Spider-Man to rescue Betty Brant from Dr. Octopus, Liz recognized Peter's bravery - and actually developed a crush on him. Peter did not reciprocate Liz's interest while his heart belonged to Betty, but Liz's flirting with him irked Flash so greatly that it led the rivals to a boxing match and a prom-night dare on the unprotected edge of a bridge.
After graduation, Liz left Flash and the old crowd behind. She became a nurse's aid, privately tending to her stepbrother, Mark Raxton, the Molten Man. Sometime later, Liz returned to Peter's life. The Molten Man was out of control, and she sought Peter for some levelheaded advice. Liz joined Peter's inner circle of friends where she met Harry Osborn, who had returned from psychiatric care after becoming the Green Goblin. Liz and Harry began dating following Harry's heroics at Betty's wedding and the two fell in love. Liz worked at a hospital while Harry prepared to take over his father's company, but she was arrested trying to steal chemicals from her workplace to help the Molten Man deal with his fiery condition. Ashamed, and fearful of damaging her boyfriend's reputation, Liz left Harry. Later, after tackling the Green Goblin (Bart Hamilton) with Spider-Man, Harry returned home to find Liz waiting for him. With Harry's new responsibilities at Osborn Industries, the couple left for the New Jersey suburbs and married, seeking a peaceful life.
That peace was short-lived thanks to both Molten Man and Hobgoblin (Roderick Kingsley) threatening the Osborn family. After a difficult labor brought on by the trauma of facing the Hobgoblin, Liz gave birth to a son, Norman Harold Osborn, and asked Peter and Mary Jane to be the godparents. When the Parkers were evicted, Harry and Liz took them in as tenants. Harry began to lose mental stability again and returned to menacing Spider-Man as the Green Goblin. Liz drifted into a state of denial, unable to cope with her husband's madness. Tragically, Harry was poisoned by an experimental Goblin formula, leaving Liz a young widow. Following Harry's death, Liz took over his responsibilities within Osborn Industries. During this time, she endured the kidnapping of her son by robotic Goblinettes left behind by Harry. "Normie" was rescued by Spider-Man and the reformed Molten Man. Upon her father-in-law's return from the "dead," Liz lost control of the company. She dated Foggy Nelson for a short time until Mysterio intervened in the relationship. She currently resides in Riverdale, New York, and remains one of Peter Parker's oldest friends. Their relationship was recently strained, however, when she was forced to lure Peter to her home under false pretenses while the Chameleon's Exterminators team awaited their prey.
In the aftermath of Spider-Man accepting an offer from Mephisto to save the life of his Aunt May in exchange for removing his marriage to Mary Jane from ever occurring in history, Harry Osborn has also somehow returned to life. He and Liz are divorced; the details of what transpired differently in time are unrevealed.