She is portrayed by Mackenzie Foy.
She has the same facial features and hair color as Edward, but has curly hair inherited from her grandfather, Charlie Swan, and brown eyes like Bella. Her heart pumps blood, giving her a blush, and her pale skin slightly glows in sunlight. Her skin is warm and soft to the touch, but it is as strong as a vampire's. Only minutes after she is born, she is imprinted upon by Jacob Black, who becomes her soul mate and acts as an older brother figure to her. Renesmee can survive on either blood or human food, though she prefers blood, and she does not produce venom. Her special abilities are transmitting thoughts to others by touching their skin and penetrating mental shields, the opposite abilities of each of her parents. She rapidly grows both mentally and physically, is able to speak only seven days after her birth, and by the end of the novel can read, run, hunt, and perform other tasks at advanced levels for her young age. Her intelligence stuns everyone, and she is able to understand what is happening around her when the Volturi arrive. Jacob nicknames her "Nessie" because he considers her full name to be a mouthful, though Bella strongly dislikes her child being nicknamed "after the Loch Ness Monster." By the book's end, however, all of the characters have adopted this shortened version. She will reach physical maturity after about seven years, when her appearance will be around 17, and then stop aging.
She is born on September 10, three days before Bella's nineteenth birthday.
Weeks after Renesmee is born, Irina, a vampire from the Denali coven, sees Renesmee and believes she is an "immortal child", a young human child who had been changed into a vampire. She informs the Volturi, as immortal children are not permitted to exist due to their unpredictable nature. Intent on killing Renesmee and the other Cullens, the Volturi travel to Forks. The Cullens gather witnesses from around the world to testify that they have seen her mature and grow, and so she is therefore not an immortal child. Alice brings another half-breed, 150-year-old Nahuel, who explains that half-breeds pose no danger to the vampires. Convinced that Renesmee is not a threat, the Volturi leave, and Renesmee and her family are left in peace.
- Her name is derived from the amalgamation of the names of Bella's mother, Renée, and Edward's adoptive mother, Esme. Her middle name, Carlie, is a portmanteau of the names Carlisle, Edward's adoptive father, and Charlie, Bella's father.