Answer: Harry S Truman

George W. Bush, John F. Kennedy, Rutherford B. Hayes–there are many U.S. presidents with prominent middle initials. In the case of Harry S. Truman, however, there’s a bit of an anomaly. Although we could hardly fault you for guessing that the S. stands for something like Samuel, Sebastian, or Sherman, it actually stands for “S” and nothing more.

In a 1962 interview, a reporter asked Truman why his name sometimes appeared in print without a period after his middle initial. He explained that it wasn’t a middle initial at all, but that his middle name was in fact simply “S.” Why the peculiarly terse middle name? His parents couldn’t decide which of his grandfathers to name him after: Anderson Shipp Truman or Solomon Young. As a compromise, they made his middle name “S” as a nod to elements of both his grandfathers’ names.

Although technically his name should be written “Harry S Truman” just like one would write “John Fitzgerald Kennedy,” stylistically it looks odd and it’s a nightmare for copy editing if the copy editor is not aware of the interesting history of Truman’s name. As such, it is common practice for both Truman’s name and any name wherein the middle name is a single letter to include a period after it.