Marcos Portugal was a Portuguese classical composer, who achieved great fame for his operas in Italian. He was a brother of Simão Victorino Portugal.

Portugal was born in Lisbon. He first studied at the Patriarchal Seminary of Lisbon, where he learned music. He wrote his first work, Misere, at age 14. He was later the organist at the See of Lisbon, and maestro at the Theatre of Salitre in Lisbon. He lived in Naples, Italy, from 1790 to 1800 on a government scholarship. He wrote 21 operas while in Italy, the first being Ill Demofoonte, which premiered in La Scala in Milan on March 8, 1794. Four other operas by Portugal were performed during his stay in Italy.

Portugal returned to Portugal in 1800. He became the master of the Royal Chapel and of the Teatro Nacional de São Carlos in Lisbon. He was also teacher of the Seminary of Lisbon and of the royal princes. He continued to write music until moving to Brazil in 1807 because of the Peninsular War. He wrote mainly religious music until 1817. After that, he was unable to compose anymore, and lived in Brazil the rest of his life. He died in Rio de Janeiro in 1830.