Ghiyath al-Din (), also transcribed as Ghiyāthu'd-Dīn, Ghiyasuddin, etc. is the name of many persons in the Islamic world. It may refer to:
People Ghiyath ad-Din Muhammad Tapar (died 1118), Sultan of the Seljuk Empire Ghiyath al-Din Abu'l-Fath Umar ibn Ibrahim Al-Nishapuri al-Khayyami, better known as Omar Khayyam, (1048–1131), Persian scientist and poet Ghiyasuddin Iwaz Shah (1150–1227), Ruler of Bengal Ghiyath al-Din Muhammad (fl. 1176–1200), ruler of the Ghorid dynasty in Khorāsān Ghīyāth al-Dīn Kaykhusraw bin Qilij Arslān, or Kaykhusraw I (died 1211), Seljuk Sultan of Rum Ghīyāth al-Dīn Kaykhusraw bin Kayqubād, or Kaykhusraw II (died 1246), Seljuk Sultan of Rum Ghīyāth al-Dīn Kaykhusraw bin Qilij Arslān, or Kaykhusraw III (died 1284), Seljuk Sultan of Rum Ghiyas ud din Balban (1200–1287), Sultan of Delhi Ghiyath al-Din Tughluq (died 1325), Sultan of Delhi Ghiyasuddin Bahadur Shah (died 1328), Sultan of Lakhnauti Ghiyas al-Din ibn Rashid al-Din, (died 1336), Ilkhanate politician Ghiyasuddin Tughluq Khan (died 1389), Sultan of Delhi Ghiyasuddin Baysunghur (1397–1433) son and associate of the Timurid ruler Shah Rukh in Herat Ghiyāth al-dīn Naqqāsh (fl. 1419–1422), the diarist of a Persian embassy to China Ghiyāth al-Dīn Jamshīd ibn Masʾūd al-Kāshī, or just Jamshīd al-Kāshī (c. 1380–1429), Persian astronomer and mathematician Ghiyasuddin Azam Shah (1390–1411), Sultan of Bengal Ghiyāth al-Dīn ʿAlī Iṣfahānī, fifteenth century, scholar in Badakhshān Ghiyath al-Din Shah Rukh Shahi Khan, Sultan of Kashmir Ghiyath Shah (1469–1500), Sultan of Malwa Ghiyasuddin Mahmud Shah (deposed 1538), Sultan of Bengal Ghiyasuddin Bahadur Shah II (r. 1555–1561), Sultan of Bengal Ghiyasuddin Jalal Shah (died 1563), Sultan of Bengal Muhammed Ghiya'as ud-din (fl. 1766–1773), Sultan of the Maldives Musa Ghiatuddin Riayat Shah of Selangor (1893–1955), Sultan of Selangor Ghayasuddin Pathan (1897–1963), Bengali politician Ghiasuddin Ahmad (born 1927), Indian-Bengali politician Ghyasuddin Ahmed (1933–1971), Bengali lecturer and historian Ghayasuddin Siddiqui (born 1939?), British-Pakistani academic and political activist T. M. Giasuddin Ahmed (1937–2020), Bangladeshi politician and former minister Muhammad Gias Uddin (born 1952), Bangladeshi politician Gias Uddin Ahmed (1954–2002), Bangladeshi politician and army officer Giasuddin Molla (born 1956), Indian-Bengali politician Giasuddin Selim, Bangladeshi film director Giasuddin Al Mamun, Bangladeshi businessman and owner of Channel 1 Giasuddin Quader Chowdhury, Bangladeshi politician Gias Uddin Chowdhury, Bangladeshi politician Gyasuddin Shaikh, Indian politician
Places Ghiyasuddin International School, Malé, Maldives. – School named after Sultan Muhammed Ghiya'as ud-din. Giasuddin Islamic Model College, Narayanganj, Bangladesh. – School named after former MP Muhammad Gias Uddin.
See also A. K. Muhammad Ghaus Uddin (died 2019), Bangladeshi politician