Mohammad-Reza Shajarian (Persian: محمدرضا شجريان‎‎) (born 23 September 1940) is an internationally and critically acclaimed Persian classical singer, composer and Ostad (master) of Persian music. He has been called "Iran's greatest living master of traditional Persian music." Shajarian is also known for his skills in Persian calligraphy, and humanitarian activities. Shajarian was born in Mashhad, Iran, and started singing at the age of five, under the supervision of his father.