Adam Eddington III is a major character in three young adult novels by Madeleine L'Engle. A marine biology student, he is the protagonist of The Arm of the Starfish (1965), and a reluctant romantic love interest for Vicky Austin in A Ring of Endless Light (1980), a romantic relationship that continues in Troubling a Star (1994). He is one of three characters to have major appearances in both L'Engle's O'Keefe family series of books and her Austin family series.