William Henry Harrison had the shortest term in office of any U.S. President. He died of pneumonia one month after his inauguration in 1841.
IMAGE: By Albert Sands Southworth (American, 1811–1894) and Josiah Johnson Hawes (American, 1808–1901). Edited by: Fallschirmjäger - The Metropolitan Museum of Art, Accession number: 37.14.44. Search for "William Henry Harrison" on the museum's site., Public Domain, https://commons.wikimedia.org/w/index.php?curid=7588819