Athelstan Frederick Spilhaus (November 25, 1911 - March 30, 1998) was a South African-American geophysicist and oceanographer. He was born in Cape Town, South Africa. He became a US citizen in 1946. Among other accomplishments, Spilhaus is credited with proposing the establishment of Sea Grant Colleges in 1964 as a parallel to the successful land-grant colleges.
In 1936 Spilhaus joined the Woods Hole Oceanographic Institution in Massachusetts, where he developed the bathythermograph, which made the measurement of ocean depths and temperatures from a moving vessel possible, a device which proved indispensable to submarine warfare. This invention established his international reputation.
Spilhaus was also chair of the scientific advisory committee of the American Newspaper Publishers Association. He became known by the public for his "Our New Age" Sunday feature, which appeared in the color comics section of 93 newspapers (1957-1973).