Osha is a wildling who was traveling in a group led by Stiv, a Night Watch deserter. She later becomes a servant of House Stark after being captured. She is a tall woman with shaggy dark hair. She is knowledgable about the forest, using spears, and the Old Gods.

In A Game of Thrones, she is with a group led by Stiv, a Night Watch deserter, trying to escape the Others, and they flee south of the Wall. They encounter Bran Stark and at first they are going to rob him and steal his horse, but then they think to ransom him back to Winterfell. Osha thinks they should take him back to Mance Rayder to be a hostage, but she is over ruled. They are defeated by Theon Greyjoy, Robb Stark, Grey Wind and Summer. All of the group is killed except for Osha, who is taken to Winterfell for interrogation, but winds up being granted the position of a servant working in the kitchen under the winterfell baker (literally and figuratively). She says that she likes the smell of flour on his hands. She also says that if she lets him do what he wants under her skirt whenever he feels the need, then he lets her go to the Godswood to pray whenever she feels the need. It is in the Godwood talking about dragons, comets, giants, and the children of the forest, that she and Bran Stark meet and eventually begin to develop a relationship.

In A Clash of Kings, after he takes Winterfell, Osha surrenders to Theon and swears fealty to him earning his trust. She and the Reeds make an escape plan. Osha takes a plate of food to a guard,and seduces him. While he is distracted she slits his throat. Then Meera Reed and Jojen Reed let the Direwolves out of the Godswood and the wolves kill the guard on the Wall. She then leaves Winterfell with Hodor, Rickon, and Bran, but they only go as far as the woods. The wolves go on to make a false trail, while they backtrack back to hide in the crypts. They hide there to get away from Theon, hoping to complete their escape after the search for them has ended. When they come out two weeks later, it is to find Winterfell burned. Finding a badly injured Maester Luwin under the heart tree, Osha answers his request to be given the gift of mercy. He tells them that he doesn't know where they should go, as there are so many invaders fighting over the North and the roads aren't safe. However, they should separate with neither knowing where the other has gone. Osha leaves with Rickon and Shaggydog saying that she might try the Kingsroad, which is not her plan.

In A Dance with Dragons, it is revealed that Osha took Shaggydog and Rickon to Skagos. This is related to Davos by Wyman Manderly at White Harbour.