Thomas Ustick Walter (September 4, 1804 – October 30, 1887) was an American architect. He worked on more than 400 projects, including Moyamensing Prison and Girard College in Philadelphia. He served as the fourth Architect of the Capitol, and led the addition of the north and south wings and the central dome. He retired in 1865, but financial difficulties forced him back to work in the 1870s, including a job as Chief Assistant to the Architect of Philadelphia City Hall.
A founder of the American Institute of Architects, he served as its president from 1876 to 1887.