Alessandro Marcello (August 24, 1669 - June 19, 1747) was a Italian nobleman who dabbled in various areas, including poetry, philosophy, mathematics and, perhaps most notably, music.

Marcello composed and published several sets of concerti (including six under the title La cetra) and some cantatas, often under the pseudonym Eterio Stinfalico. Although his works are performed extremely infrequently today, he is regarded as a very competent composer. Johann Sebastian Bach arranged an oboe concerto in D minor by him for harpsichord (BWV 974). This oboe concerto is perhaps Marcello's best-known work.

Alessandro's brother was Benedetto Marcello, also a composer.