Humankind has long possessed a fascination with the cosmos and the cosmic bodies they can see from their earthly home. Overtime humans began to associate deities with the cosmic bodies, and religions developed to explain the cosmos and humans' place within it. Early humans created artifacts, using the imagery of cosmic bodies to mark the passage of time and to symbolize their relationship to the cosmos. When they began writing, this use of the cosmic bodies appeared in their literary works and in the works of Ancient Greek and Roman playwrights, William Shakespeare, Arthur Miller, and Thornton Wilder, among many others. Musical theatre, integrated into a unique theatre genre in the mid-twentieth century, similarly followed this impulse to use cosmic bodies to elucidate character and themes. The relationship of these instances, however, to the long traditional symbolic use of cosmic symbolism in Western thought and the ways in which the cosmic symbolism reveals character traits has been largely overlooked in musical theatre scholarship. This analysis contributes the first book-length study investigating cosmic symbolism in selected, representative musicals that span the time period from the American Golden Age through the present. Aided by available scholarship from the fields of astrology, anthropology, psychology, semiotics, religious studies, and philosophy this study aims to increase understanding of how cosmic symbolism functions within representative musical theatre works and what that symbolism reveals about humans' interactions with the cosmos.