Ulugh Beg (March 22, 1394 in Sultaniyeh, Persia – October 27, 1449, Samarkand) was a Timurid ruler, as well as an astronomer, mathematician and sultan. His commonly known name is not truly a personal name, but rather a moniker, which can be loosely translated as "Great Ruler" or "Patriarch Ruler", and was the Turkic equivalent of Timur's Perso-Arabic title Amīr-e Kabīr. His real name was Mīrzā Mohammad Tāraghay bin Shāhrokh. Ulugh Beg was also notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry. He built the great Ulugh Beg Observatory in Samarkand between 1424 and 1429. It was considered by scholars to have been one of the finest observatories in the Islamic world at the time, and the largest in Central Asia.

Ulugh Beg was also a mathematics genius of the 15th century — albeit his mental aptitude was perseverance rather than any unusual endowment of intellect. His Observatory is situated in Samarkand which is in Uzbekistan. He ruled Uzbekistan, Tajikistan, Turkmenistan, Kyrgyzstan, southern Kazakhstan and most of Afghanistan from 1411 to 1449.

The Ulugh Beg Observatory Museum was built in 1970 to commemorate Ulug Begh. Copies of Ulugh Beg's Star Charts, the Zij-i Sultani, are kept in the museum; the original drawings are in Oxford, England.