Marseillan is a commune in the Hérault department in southern France. It lies some 50 km (31 mi) west of Montpellier.

Marseillan sits on a large lagoon, the Étang de Thau, and is the southern entreport for the Canal du Midi.

The village is tranquil, with its heart still within the lines of the old walls. There is one small hotel and some 18 cafes and restaurants. For sun, sea and sand there is Marseillan Plage, a purpose built holiday resort on the Mediterranean itself, some 3 km (1.9 mi) from Marseillan Ville.

The port is a protected heritage site, and the altar and organ in the church are also listed. There has been virtually no new building in the heart of the village since the 17th century, and many of the houses date from the twelfth century.

Until 1970 the vineyards came to the main boulevards built outside the line of the walls around 1870. Since then the population has grown from around 3,000 throughout the last 200 years to over 10,000 in 2010. This does not include those who have bought houses and villas in Marseillan but use them only as holiday homes. Expectation is that the population will top 14,000 by 2015.