Several scholars have studied meanings attributed to the lion in the western European Middle Ages, but their accounts have tended to be partial and fragmentary. A balanced, coherent interpretive history of the medieval lion has yet to be written. This article seeks to promote and initiate the process of composing such a history by briefly reviewing previous research, by proposing a thematic and chronological framework on which work on the lion might reliably be based, and by itself discussing numerous textual examples, not least from German, Latin, and French literature. The five categories of lion symbolism covered are, respectively, the threatening lion, the Christian lion, the noble lion, the sinful lion, and the clement lion. These meanings are shown successively to have constituted regnant fashions that at various times profoundly shaped people's understanding of the lion; but it is demonstrated also that they existed alongside, and in a state of creative tension with, a “ground bass” of lion meanings that changed relatively little. Lions nearly always, for example, represented important, imposing things and people (for example, kings); and the New Testament's polarized presentation of the lion as either Christ or the devil proved enormously influential both throughout and beyond the Middle Ages. As such any cultural history of the lion — and indeed of many other natural phenomena — must be continually sensitive to the co-existence and interaction of tradition and innovation, stability and dynamism.