Thomas Roney Williamson (October 30, 1852 – September 12, 1896) was an American architect based in Philadelphia and West Chester, Pennsylvania.

[1][2] On September 12, 1896, Williamson died suddenly of a heart attack while vacationing at the seaside cottage of his friend Thomas S. Butler in Longport, New Jersey.

Williamson was among the handful of Pennsylvania architects to use serpentine routinely in their projects, designing West Chester University's Recitation Hall, a large gym modeled on Harvard's Hemenway Gymnasium, an auditorium that could seat nearly a thousand people, and the house of college president George Morris Philips (known as "Green Gables").

Also constructed of serpentine were Williamson's 1889 tower (since demolished) and 1892 choir building of West Chester's Holy Trinity Episcopal Church.

[1][8] In 1890, Williamson authored a "Pamphlet on Building, Lighting, Heating, Ventilating and Repairing Schoolhouses, together with Hints on the Care and Construction of Out Houses," copies of which went out to all school directors in Chester County.