Hermotimus of Colophon (4th century BC) was an Ancient Greek mathematician who lived and worked in Colophon. He is known only from a single sentence by Proclus, probably summarizing a lost work of Eudemus of Rhodes. This sentence states that Hermotimus continued the research of Eudoxus and Theaetetus, discovered many of the propositions in Euclid's Elements, and wrote about theorems on loci.