Didymograptus is a genus of graptolite that lived from the early to late Ordovician of South America, North America, Europe, Asia, Africa, and Oceania. Like other graptolites, it was a colonial animal, with individual zooids within the tubarium, or colony structure. In Didymograptus's case the shape of the colony resembles that of a tuning fork. It was a filter feeder that would have floated in the water column, with the zooids using their small arms catch food. The genus was named by McCoy in 1851.