Harold Frank Hoar, FRIBA (13 September 1909 – 3 October 1976) was a British architect, artist, academic and architectural historian. Hoar first came to public prominence when, at the age of 25, he won a competition to design the first terminal building at London's Gatwick Airport in the 1930s. His architectural career focused increasingly on town planning in the post war years, when he also became a well known public commentator on domestic architecture in that era of reconstruction. A senior lecturer at University College London, Hoar was an expert on the Bavarian Baroque and wrote histories of English and European architecture at a time when architectural modernism decried the value of an historical approach to architecture. He was also an accomplished watercolour painter, his work on architectural themes having often been exhibited in the Royal Academy in the 1950s and 1960s.
In a wide-ranging career Hoar was probably best known as the cartoonist "Acanthus", where his work appeared in Punch, the Sunday Telegraph, The New Yorker and The Builder magazine; and as "Hope" in the Sunday Express. His cartoons reflected on the home front during the Second World War and were often accompanied by great architectural backdrops. As a cartoonist during the war, Hoar's political cartoons contemplated the long term direction of the war and of the perpetrators of its worst atrocities.