The Last Light of the Sun is a 2004 fantasy novel by Canadian writer Guy Gavriel Kay. Like many of his books, it is set in a world that draws heavily upon real times, events, places and people. In this particular book, the period is the Viking invasions of Saxon England. The story concerns a young Erling's attempt to prove himself as a warrior, his father's attempts to make amends for his mistakes, a young prince searching for revenge and a King's attempt to transform his realm into a more civilized one that will resist attacks from the Erlings forever. The books main themes are revenge, violence, the passing of an era, clash of cultures, and love, especially between father and son.

Guy Gavriel Kay is a Canadian writer of fantasy fiction. The majority of his novels take place in fictional settings that resemble real places during real historical periods, such as Constantinople during the reign of Justinian I or Spain during the time of El Cid. Kay has expressed a preference to avoid genre categorization of these works as historical fantasy. As of 2022, Kay has published 15 novels and a book of poetry. As of 2018, his fiction has been translated into at least 22 languages. Kay is also a qualified lawyer in Canada.