Theophil Hansen (*1813 in Copenhagen, †1891 in Vienna) was a Danish-Austrian architect and an important figure in classicism and historicism.

After an apprenticeship with Karl Friedrich Schinkel and studies in Vienna, the young Hansen moved to Athens to study Greek architecture. His first ever commission was the Athens Observatory. Back in Vienna, Hansen became an outstanding representative of Renaissance-oriented stringent historicism, a characteristic found in even the smallest details of his interior designs. Starting in 1858, demolition of the Vienna city walls and replacement by the Ringstrasse began in Vienna, with Hansen becoming one of its most important architects. 

The Palais Hansen was built from 1869 to 1873 and the Vienna Stock Exchange from 1873 to 1877, both on Schottenring. His most well-known work was the Vienna Parliament in 1883, designed in the style of an Attic temple in a nod to Greek democracy. In 1870, the Musikverein opened its doors, the much-admired acoustics of which are still imitated by concert halls today. For Lobmeyr he designed crystal and lighting.