Appleton Prentiss Clark Jr. (November 13, 1865 – March 25, 1955) was an American architect from Washington, D.C. During his 60-year career, Clark was responsible for designing hundreds of buildings in the Washington area, including homes, hotels, churches, apartments and commercial properties. He is considered one of the city's most prominent and influential architects from the late 19th and early 20th centuries. Many of his designs are now listed on the National Register of Historic Places (NRHP).