Graeco-Phrygian (/ˌɡriːkoʊˈfrɪdʒiən/) is a proposed subgroup of the Indo-European language family which comprises the Hellenic and Phrygian languages.

Modern consensus views Greek as the closest relative of Phrygian, a position that is supported by Brixhe, Neumann, Matzinger, Woodhouse, Ligorio, Lubotsky, and Obrador-Cursach. Furthermore, out of 36 isoglosses collected by Obrador Cursach, Phrygian shared 34 with Greek, with 22 being exclusive between them. The last 50 years of Phrygian scholarship developed a hypothesis that proposes a proto-Graeco-Phrygian stage out of which Greek and Phrygian originated, and if Phrygian was more sufficiently attested, that stage could perhaps be reconstructed.

The linguist Claude Brixhe points to the following features Greek and Phrygian are known to have in common and in common with no other language:

Obrador-Cursach (2019) has presented further phonetic, morphological and lexical evidence supporting a close relation between Greek and Phrygian, as seen in the following tables that compare the different isoglosses between Phrygian, Greek, Armenian, Albanian and Indo-Iranian.

Greek and Ancient Macedonian are either classified under Hellenic as sister languages, or according to most scholars Ancient Macedonian is seen as a Greek dialect. Hellenic has also been variously grouped with Armenian and Indo-Iranian (Graeco-Armenian; Graeco-Aryan) and, more recently, Messapic. The linguist Václav Blažek states that, in regard to the classification of these languages, "the lexical corpora do not allow any quantification" (see corpus and quantitative comparative linguistics).