Critolaus of Phaselis was a Hellenistic historian of the 2nd century BCE. He is known only from fragmentary references, identified by his origin in the Lycian city of Phaselis. No details of his life or education survive.

He is credited with a single lost work, the History of Phocis. It is cited solely by the travel writer Pausanias, who references Critolaus for a casualty figure during the Third Sacred War. His significance rests on being a representative of Hellenistic local historiography. His use by Pausanias indicates his work was considered a reliable authority on Phocian affairs, though its full scope is otherwise unknown.