Lennie Walker is a fictional character from the novel "The Sky is Everywhere" by Jandy Nelson. She is a teenage girl navigating the complexities of grief after the death of her sister, Bailey. Lennie is passionate about music and poetry, using these creative outlets to express her emotions and cope with her loss. Throughout the story, Lennie experiences a journey of self-discovery, exploring her relationships with friends and potential love interests, including Joe and Toby. Her character embodies themes of love, loss, and the struggle to find one's identity in the face of tragedy.