| Named By: | Harry Govier Seeley in 1887 |
| Time Period: | Early Cretaceous, 125 Ma |
| Location: | England - Wessex Formation |
| Size: | Uncertain due to lack of fossils, but comparison to related genera suggests that Ornithodesmus grew to roughly about 1.8 meters long |
| Diet: | Carnivore |
| Fossil(s): | Sacral vertebrae |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Theropoda | Dromaeosauridae | |
Ornithodesmus (meaning "bird link") is a genus of small, dromaeosaurid dinosaur from the Isle of Wight in England, dating to about 125 million years ago. The name was originally assigned to a bird-like sacrum (a series of vertebrae fused to the hip bones), initially believed to come from a bird and subsequently identified as a pterosaur. More complete pterosaur remains were later assigned to Ornithodesmus, until recently a detailed analysis determined that the original specimen in fact came from a small theropod, specifically a dromaeosaur. All pterosaurian material previously assigned to this genus has been renamed Istiodactylus.