Rosalie Lillian Hale was born to a middle-class family in 1915 in Rochester, New York. Her father had a stable job in a bank while her mother was a housewife. Her parents were social climbers and Rosalie, who was extraordinarily beautiful, was the ticket they needed to reach their social aspiration. She was clearly the favorite of her parents, with two younger brothers.
While growing up, Rosalie dreamed of a lavish life--a life with a rich husband and children as beautiful as she was. Her parents influenced her want of material things, which made her vain and conceited. She wanted a big house that someone else would clean, with a large lawn that she would play with her children on.
In Rochester, where she grew up, there was only one family that had what her parents wanted--the Kings. Royce King owned the bank Rosalie's father worked in. His son, Royce II, saw Rosalie for the first time and began dating her. It was a quick courtship and the couple was soon engaged. The engagement went too quickly and wedding plans were made.
Rosalie couldn't help but feel something was missing from her relationship with him, despite the fact that Royce was everything she'd dreamt of. She soon began wanting what her good friend Vera had--a husband who wasn't necessarily rich, but one that loved her and was there for her, and a small baby they could raise together lovingly.
One night she went to Vera's, and while walking home she realized how late it was and she wished that she had called her father to escort her but realized it was silly since the way was so short. As she continued, she saw several drunken men. One of them turned out be Royce. Showing her off to his friends, he ripped off her jacket and the pins from her hair. When she cried out in pain, the men seemed to enjoy it. They proceeded to beat and later rape her.
Royce and his friends left her dying on the streets. Carlisle Cullen came to investigate the grisly scene, found her half-dead and tried to save her humanly. Rosalie had never liked Dr. Cullen or his wife, Esme and her brother, Edward, as he then pretended to be. It had bothered her that the family was more beautiful than she was. Dr. Cullen, who turned out to be a vampire, saved Rosalie that night by turning her into a vampire after he realized she could not survive her wounds as a human. Despite the fact he and his family are vampires, they only fed on the blood of animals, calling themselves "vegetarians". Soon after becoming a vampire, she killed Royce and his friends in vengeance but was careful not to spill a drop of blood, knowing she couldn't resist that. For this particular reason, Rosalie prides herself on never having fed on human blood.
Two years later, while hunting, she found a young man named Emmett being mauled by a bear and ran him back to Carlisle. She begged for him to save the dying Emmett, who reminded her of Vera's little boy Henry, by changing him into a vampire. The two fell in love and were soon married.
Rosalie and Emmett currently reside in Forks, Washington, but they often live away from the family as a married couple. Rosalie is the only one of the Cullens (except Carlisle) to keep her last name, on account of her not wanting to be a vampire. It is for this reason that she resents Bella for wanting to be a vampire, for "throwing away" everything Rose ever wanted but never had a chance to have.
Rosalie is described as being astoundingly beautiful, even for a vampire. She is tall, statuesque and has wavy blonde hair to the middle of her back. She is physically 18 years old.