Leodamas of Thasos (c. 380 BC) was a Greek mathematician and a contemporary of Plato, about whom little is known.
There are two references to Leodamas in Proclus's Commentary on Euclid:
"At this time also lived Leodamas of Thasos, Archytas of Tarentum, and Theaetetus of Athens, by whom the theorems were increased in number and brought into a more scientific arrangement. Younger than Leodamas was Neoclides and his pupil Leon, who added many discoveries."
"Plato, it is said, taught this method to Leodamas, who is also reported to have made many discoveries in geometry by means of it."
and one in Diogenes Laertius' Lives and Opinions of Eminent Philosophers, Book 3 (Plato):
"He was the first to explain to Leodamas of Thasos the method of solving problems by analysis."