Sayyid Theyazin bin Haitham Al Said (Arabic: ذي يزن بن هيثم آل سعيد, romanized: Ḏī Yazin bin Hayṯam ʾĀl Saʿīd; born 21 August 1990) is the Crown Prince of Oman and the Minister of Culture, Sports and Youth.

Theyazin is the eldest son of Sultan Haitham bin Tariq and Sayyida Ahad bint Abdullah. He has one younger brother and two sisters. His paternal uncle, Sayyid Asa'ad bin Tariq, is the Deputy Prime Minister for Relations and International Cooperation Affairs, and another paternal uncle, Sayyid Shihab bin Tariq, is the Deputy Prime Minister for Defense Affairs. The former Sultan, Qaboos bin Said, was his father's cousin.

He earned a bachelor's degree in political science from the University of Oxford and a master's degree in history from Oxford Brookes University. In July 2022, he graduated from the Royal Military Academy Sandhurst.

In January 2021, Theyazin became engaged to Sayyida Meyyan bint Shihab bin Tariq Al Said. The couple are first cousins twice over since their fathers are brothers and their mothers are sisters. They were married on 11 November 2021 in the Mazay Hall of Al Alam Palace. Emirati singer Ahlam and Lebanese singer Myriam Fares performed during the celebrations. The couple were divorced in early 2022.

In January 2025, it was announced that Theyazin was engaged again. In April, it was revealed that Theyazin is set to marry Sayyida Alia bint Mohammed bin Hilal Al Busaidi on 24th April 2025 in the Mazay Hall of Al Alam Palace.

Theyazin was appointed the Minister of Culture, Sports and Youth following the merger of the Ministry of Sports Affairs, Ministry of Arts Affairs, and the National Youth Committee in August 2020. He previously worked for the foreign ministry starting in 2013 including serving as a second secretary for two years at the Omani Embassy in London.

On 11 January 2021, the Sultan issued a new royal decree establishing an order of succession and a crown prince role for the Sultanate. As the eldest son of the Sultan, Theyazin is the heir apparent.