Isa Muhammad Effendi or Ustad Isa (Persian: استاد عيسى translation Master Isa (Jesus in Arabic)) was a Persian architect from Iran he and his colleague Ismail Effendi entered the service of the Mughal Emperor Shah Jahan after the Ottoman Sultan Murad IV and the Mughals exchanged ambassadors. Isa Muhammad Effendi is often described as the chief architect of the Taj Mahal.
The lack of complete and reliable information as to whom the credit for the design belongs, led to innumerable speculations. Scholars suggest the story of Ustad Isa was born of the eagerness of the British in the 19th century to believe that such a beautiful building should be credited to a European architect. Local informants were reported to have sated British curiosity regarding the origins of the Taj by also supplying them with fictitious lists of workmen and materials from all over Asia. Typically, he is described as either a Turkish or Persian architect.
Recent research suggests the Persian architect, Ustad Ahmad Lahauri was the most likely candidate as the chief architect of the Taj, an assertion based on a claim made in writings by Lahauri's son Lutfullah Muhandis.