Reginald "Rex" Engelbach (9 July 1888 – 26 February 1946) was an English Egyptologist and engineer.
Initially trained in engineering, in 1908 Engelbach had to discontinue his studies due to a long illness; in 1909-10 he went to convalesce in Egypt where he became fascinated by ancient Egyptian culture.
In 1911 he started a collaboration with Sir Flinders Petrie as his assistant, excavating in various places such as Heliopolis, Riqqeh and Harageh.
In 1915 he get married and in 1920-21, after World War I, he resumed working with Petrie in his excavation at El-Lahun and Abu Gorab.
He subsequently earned a remarkable number of charges and awards and began working at the Cairo Museum.