Duca can refer to:

• Duca (footballer), Adrualdo Barroso da Silva (born 1934), Brazilian footballer
• Duca (singer) [ja] (デュッカ), Japanese female singer
• Edoardo Duca (born 1997), Italian footballer
• Ion G. Duca (1879–1933), 35th Prime Minister of Romania
• Lauren Duca (born 1991), American journalist
• Michael Duca (born 1952), American Catholic bishop
• George Ducas (Romanian: Gheorghe Duca; c. 1620–1685), three times prince of Moldavia
• Constantine Ducas (Moldavian ruler) (Romanian: Constantin Duca; died 1704), two times prince of Moldavia

• DUCA Credit Union, a Canadian credit union
• a Romanesque title of duke, notably in Italian

• Del Duca (disambiguation)
• Lo Duca, surname
• All pages with titles containing Duca