Certainly not as many who have heard the names of Carl Jung, Sigmund Freud, Jean Piaget, and Lev Vygotsky, have heard of Sabina Spielrein. While Spielrein had numerous face-to-face encounters, some personal and some professional, with all four men, and the accounting of her life and the interactions she had with them has been the content of numerous publications (Kerr, 1993; Marton, 2002), the story of what she contributed to their lives and works has not been told. In this article, the author profiles Sabina Spielrein and concisely describes how Spielrein's life, work, and theories influenced the theories of Jung, Freud, Piaget, and Vygotsky.