Phuwiangosaurus (meaning "Phu Wiang lizard") is a genus of dinosaur from the Early Cretaceous. It was a titanosaur which lived in Thailand. The type species, P. sirindhornae, was described by Martin, Buffetaut, and Suteethorn in 1994; it was named to honour Princess Maha Chakri Sirindhorn of Thailand, who was interested in the geology and palaeontology of Thailand. It was a mid-sized sauropod, measuring 15-20 m in length.