Wilhelm Altar (August 27, 1900 – January 1, 1995), known to family and colleagues as William Altar, was an Austrian-born theoretical physicist whose significant contributions led to the development of the magneto-ionic theory. Altar contributed to the mathematical and conceptual underpinnings that were verified by Appleton 's research, in collaboration with Dr. Altar. Altar was not credited with his contributions until 1982, decades after Appleton received the 1947 Nobel Prize in Physics.