Karen King is one of the best friends of Maryellen Larkin.
Karen is described as having a round, freckly face, and she is very cheerful. She is sympathetic towards Maryellen always getting hand-me-downs, as she herself gets hand-me-downs from her older sister, who is very hard on her clothes, and thinks it lucky that Karen Stohlman only has a brother. She has a knack for saying things clearly and prides herself on telling the truth no matter how unpleasant it may be, but this can often be rude or cruel.
Though she lives in a different neighborhood than Maryellen, she is in her class and Girl Scout troop (Until Maryellen stops to be part of the Science Club).