In Norse mythology, Grim (Mask) and Grimnir (Masked One) are names adopted by the deity Odin (Anglo-Saxon Woden) when travelling incognito amongst mortals, as in the short poem known as ‘Grimnir’s Sayings’ (Grimnismal) in the Poetic Edda. The intended audience of the Havelock tale (recorded much later in the form of The Lay of Havelock the Dane) may have understood the fisherman Grim to be Odin in disguise. The Odinic name ‘Grimr/Grim’ occurs in many English placenames within the historical Danelaw and elsewhere in Britain, examples being the numerous earthworks named Grimsdyke. As other British placenames containing the element Grim are explained as referring to Woden/Odin (e.g. Grimsbury, Grimspound, Grime’s Graves, Grimsditch, Grimsworne), Grimsby is likely to have the same derivation.