| Named By: | B. F. Nopcsa in 1903 |
| Time Period: | Late Cretaceous, 70 Ma |
| Location: | Romania - Transylvania - Sanpetru Formation |
| Size: | Around 5 meters long |
| Diet: | Herbivore |
| Fossil(s): | Many individuals |
| Classification: | | Chordata | Reptilia | Dinosauria | Ornithischia | Ornithopoda | Hadrosauridae | |
| Also known as: | | Hecatasaurus | Limnosaurus transsylvanicus | |
Telmatosaurus (meaning "marsh lizard") is a genus of basal hadrosaurid dinosaur from the Late Cretaceous. It was a relatively small hadrosaur, approximately five meters (16 ft) long, found in what is now Romania.