Harper is an American publishing house, the flagship imprint of global publisher HarperCollins based in New York City. Founded in New York in 1817 by James Harper and his brother John, the company operated as J. & J. Harper until 1833, when it changed its name to Harper & Brothers, reflecting the inclusion of Joseph and Fletcher Harper. Harper began publishing Harper's Magazine, Harper's Weekly, and other periodicals beginning in the 1850s. From 1962 to 1990, the company was known as Harper & Row after its merger with Row, Peterson & Company. Harper & Row was purchased in 1987 by News Corporation and combined with William Collins, Sons, its United Kingdom counterpart, in 1990 to form HarperCollins, although the Harper name has been used in its place since 2007.

HarperCollins Publishers LLC is an Anglo-American publishing company that is considered to be one of the "Big Five" English-language publishers, along with Penguin Random House, Hachette, Macmillan, and Simon & Schuster. HarperCollins is headquartered in New York City and is a subsidiary of News Corp.