Cornelia Grimm is an original character from The Land of Stories series. She first appears in Beyond the Kingdoms. She is a distant relative of Bree. Bree finds out about her through an old letter she finds in the attic with her late grandmother's things.
Appearance and Personality
"Cornelia looked a few years younger than Bree's grandmother. She had long blonde hair all the way down to her waist and the same smile as Anneliese."
Cornelia is Anneliese Campbell's cousin. Her grandparents moved the the United States from Germany when they were young. She lives in a house on Mystic Lane 1729 in Willow Grove, Connecticut, with the Sisters Grimm, a group of women who monitor the Portals and "magical phenomena" in the Otherworld. Anneliese lived with them too, until her wedding to Stephen Campbell. They were very close, but lost touch in later years.
In search of her anchestry, Bree goes to visit her and finds out Wilhelm Grimm was Cornelia and Anneliese's fourth-great-grandfather. Cornelia tells her she and several other relatives, many of them women, all lived at the house in Conneticut at some point, and probably gave the neighbours the idea they were a coven. 
"She was very old now but still looked similar to her grandma's picture. She had long white hair down to her waist. She wore red-framed glasses, and a stylish silk scarf was wrapped around her neck."
The Sisters know about the story of the Grande Armée, and Bree fills them in on the events that occurred in the Land of Stories when the Armée came out of the portal. In turn, they tell her about the sisterhood.
"We've used the most powerful force of our world to predict the locations of the magical occurence," Cornalia said. "Science!"