The Orb (French pronunciation: [ɔʁb]; Occitan: Òrb) is a 135.6-kilometre (84.3 mi) long river in the department of Hérault in the south of France. It flows into the Mediterranean Sea at Valras-Plage. The river flows through the towns of Bédarieux and Béziers, where it is crossed by the canal du Midi on the Orb Aqueduct. In ancient times, the Orb was crossed at Capestang by the 1,500-metre (4,900 ft) long Roman Pont Serme.

The Orb flows through the following communes:

• Ceilhes-et-Rocozels
• Avène
• Le Bousquet-d'Orb
• La Tour-sur-Orb
• Bédarieux
• Hérépian
• Lamalou-les-Bains
• Le Poujol-sur-Orb
• Roquebrun
• Cessenon-sur-Orb
• Lignan-sur-Orb
• Béziers
• Sauvian
• Sérignan
• Valras-Plage

• 
  Orb river bridge at Cazouls
• 
  The Orb at Roquebrun
• 
  The Orb viewed from Béziers

The following rivers flow into the Orb:

• Jaur 30 kilometres (19 mi)
• Lirou 30 kilometres (19 mi)
• Mare 29 kilometres (18 mi)
• Taurou 25 kilometres (16 mi)
• Vernazobre 24 kilometres (15 mi)
• Rieutort 18 kilometres (11 mi)
• Héric 14 kilometres (9 mi)