Oral-formulaic theory in Anglo-Saxon poetry refers to the application of the hypotheses of Milman Parry and Albert Lord on the Homeric Question to verse written in Old English.
The theory proposes that features of at least some of the poetry may be explained by positing oral-formulaic composition, meaning that poets have a store of verbal formulae which they freely recombine to form poems.
In Homeric verse, for example, a phrase like rhododaktylos eos ("rosy fingered dawn") or oinops pontos ("winedark sea") occupy a certain metrical pattern that fits, in modular fashion, into the six-colon Greek hexameter, and aid the aioidos or bard in extempore composition.
Moreover, phrases of this type would be subject to internal substitutions and adaptations, permitting flexibility in response to narrative and grammatical needs: podas okus axilleus ("swift footed Achilles") is metrically equivalent to koruthaiolos ektor ("glancing-helmed Hektor").
John Richardson held that the schema was so general as to apply to virtually any character at some point in the narrative, and thought it an instance of the "threshold" feature of Joseph Campbell's Hero's Journey monomyth.