Ian William Ridpath is an English amateur astronomer, who has been an active observer, writer, editor, and broadcaster, on the subject since 1972. He is also known for his UFO skepticism, an interest in astro-philately, marathon running (having participated in the London Marathon dressed as Halley’s Comet) and, most recently, horse racing.

Ridpath has an equally varied and productive professional life. He has written or edited over forty books in the field of astronomy, he is a Fellow of the Royal Astronomical Society (Council member 2004–07), a member of the Society of Authors, a member of the Association of British Science Writers, he has worked at the University of London Observatory, and manages a self-publishing business. He also regularly gives talks and lectures on astronomy.

He is most well known in astronomical circles as the editor of the Oxford Dictionary of Astronomy, and for his updates and work on the acclaimed classic Norton's Star Atlas.