Many entomologists are generally unacquainted with the life and scientific contributions of Benjamin Dann Walsh, the first State Entomologist of Illinois and an early proponent of Darwinian theory. This historical oversight is unfortunate because Walsh was both a pioneer in entomology and the only entomologist of his and Darwin's generation to support and contribute to Darwin's revolutionary theory of species origin. In this review, I attempt to return Walsh to his rightful place among the more fascinating and progressive scientists of the nineteenth century. The review comprises three sections: the first provides a biographical sketch of Walsh's rich and varied life in England and the United States; the second considers his entomological endeavors and legacy; and the third argues for Walsh's prescient advocacy of, and contributions to, evolutionary theory. Also included are passages from some of Walsh's publications and excerpts from his correspondence with Darwin and notable entomologists.