Agent

(1) Person/company (such as a sales representative) acting on behalf of the publisher, paid usually on a commission basis and often working to solicit book orders in a territory and ensure these are forwarded to the appropriate warehouse.

(2) Person acting on behalf of the author (usually a literary agent) who for a commission on all earnings finds a publisher for an author’s work and acts as an intermediary, securing the best possible deal. Because earnings are so poor in academic publishing, such agents are almost unheard of. By contrast, in trade publishing they have taken on much of the gatekeeping role of commissioning editors, so getting accepted by an agent is often a crucial step towards getting published.

This definition is extracted from the book Getting Published: A Companion for the Humanities and Social Sciences by Gerald Jackson and Marie Lenstrup.