This paper outlines the individual histories of the attested ancient Celtic epigraphic traditions, Cisalpine Celtic, Celtiberian, Gaulish and Ogam-Irish. It discusses the types of literacy in each of them and presents them as examples of how and under which conditions literacy arose and grew, and finally disappeared, in non-classical languages of antiquity. Where possible, the Celtic languages are viewed against an early Germanic background, to highlight similarities and parallels between the two philological areas, but also to contrast the differences between them and to give an account of where and when opportunities of literate interaction may have arisen between the two groups. These zones of potential interaction, as well as uncommon shapes of letters in some Celtic writing systems, are of relevance for the concluding section where observations from a Celtologist’s point of view will be made that may have a bearing on the origins of Runic writing.