Constantin Floros (Greek: Κωνσταντίνος Φλωρος) (b. Thessaloniki 4 January 1930) is a Greek musicologist. He studied law at the University of Thessaloniki (1947–1951) and then composition and conducting at the Vienna Music Academy. At the same time he studied musicology with Erich Schenk at Vienna University as well as art history (with C. Swoboda), philosophy and psychology. In 1955 he obtained the doctorate in Vienna with a dissertation on Campioni. He continued his musicological studies with Husmann at Hamburg University (1957–1960), where in 1961 he completed his Habilitation in musicology with a work on the Byzantine kontakion. In 1967 he became supernumerary professor, in 1972 professor of musicology and in 1995 professor emeritus at the University of Hamburg. He received the honorary doctorate from the University of Athens in 1999.
He is the co-editor of the Hamburger Jahrbuch fur Musikwissenschaft and in 1988 he founded and became president of the Gustav Mahler Vereinigung, Hamburg. In 1992 he was elected a member of the Erfurt Akademie der gemeinnützigen Wissenschaften and in 1999 was made an honorary member of the Richard Wagner-Verband, Hamburg.
Floros' interests include the origin of Gregorian neumes, various aspects of Byzantine music, connections between the music cultures of East and West, the semantic meaning of the 18th and 19th century symphony, the music of the Second Viennese School  etc.
- Einfuehrung in die Neumenkunde (Wilhelmshaven, 1980; Enlarged Greek edition, 1998)
- "Das Kontakion," Deutsche Vierteljahrsschrift für Literaturwissenschaft und Geistesgeschichte, xxxiv (1960), 84-106, "Fragen zum musikalischen und metrischen Aufbau der Kontakien," Congres d'etudes byzantines XII, Ohrid 1961, ii, 563-9, "Die Musik der Ostkirche," Das Buch der heiligen Gesänge der Ostkirche, ed. E. Benz, C. Floros and H. Thurn (Hamburg, 1962), 143-74
- "Ueber Zusammenhaenge zwischen den Musikkulturen des Ostens und des Westens im Mittelalter," Musica antiqua IV, Bydgoszcz 1975, 319-40
- "Die Thematik in Johann Sebastian Bachs Orchestersuiten," SMw, xxv (1962), 193-204, Gustav Mahler, i: Die geistige Welt Gustav Mahlers in systemischer Darstellung (Wiesbaden, 1977); ii: Mahler und die symphonik des 19. Jahrhunderts in neuer Deutung (Wiesbaden, 1977); iii: Die Symphonien (Wiesbaden, 1985; Eng. trans., 1993), Brahms und Bruckner: Studien zur musikalischen Exegetik (Wiesbaden, 1980)
- "Kompositionstechnische Probleme der atonalen Musik," GfMKB, Kassel 1962, 257-60, "Das esoterische Programm der Lyrischen Suite von Alban Berg: eine semantische Analyse," HJbMw, i (1975), 101-45
- The New Grove Dictionary of Music and Musicians