John B. Halcott (1846–1895) was an American architect who worked in New York State and in North Carolina. In North Carolina, he was credited with architectural design of the New York State Capitol, which everywhere else is credited to others.
Built in 1883 by contractors Mull & Fromer, the Greene County Office Building in Cairo, New York, formerly the Greene County Alms House, was designed by John B. Halcott (1846–1895), architect.
In North Carolina, he designed:
and other works.