Alfred T. Fellheimer (March 9, 1875 – 1959) was an American architect. He began his career with Reed & Stem, where he was lead architect for Grand Central Terminal. Beginning in 1928, his firm Fellheimer & Wagner designed Cincinnati Union Terminal.
In 1898, he joined the firm of Frost & Granger. In 1903 he joined Reed and Stem. As a junior partner he was lead architect in Reed & Stem's partnership with Warren and Wetmore to design Grand Central Terminal during its construction, starting in 1903. Following the death of Charles Reed in 1911 he became a named partner of Stem & Fellheimer which designed Union Station (Utica, New York) in 1913. The firm became Fellheimer & Long with Allen H. Stem Associated Architects in 1914 and designed the Morris Park (IRT Dyre Avenue Line) in the Bronx.
In 1923 he and an associate, Steward Wagner, from the earlier firm formed Fellheimer & Wagner and designed the Union Station in Erie, Pennsylvania. The firm completed the Cincinnati station in 1933. In 1939 the firm had a commission to do a complete overhaul of the CBS Studio Building.
The firm became Fellheimer, Wagner & Vollmer which designed the Farragut Houses project in Brooklyn starting in 1942. and the Albany Houses complex in Brooklyn starting in 1950 for the New York City Housing Authority.
In 1951, the firm designed a new Montclair, New Jersey branch store with Roland Wank for Newark-based Hahne & Company. In 1952, Fellheimer & Wagner designed the Beekman Theatre in New York City.