Walter Breuning (September 21, 1896 – April 14, 2011) was an American supercentenarian and former railroader, and at the time of his death the oldest living man in the world after the death of British World War I-veteran Henry Allingham (who was 15 weeks, 2 days older) on July 18, 2009, and the oldest living man in the United States since December 27, 2008 upon the death of George Francis (who was born on the same day as Allingham). He was also a colorectal cancer survivor.