The name, in various forms, shows up in medieval Frankish and Germanic literature as the name of important legendary and semi-legendary kings.

Austria

Latin

● 1074x1087 Guntherus (nom) UrkStyria 77; c1075 Guntheri (gen) ibid. 78; 1103 Guntheri (nom) ibid. 95; c1130 Gunther (nom) ibid. 124; 1277 Gunthero (abl) FRA-XXXL 355

Belgium

Latin

● 1106 Gontero (abl) CartStBert 2

Czech Republic

Middle High German

● 1318 Gvnther (nom) Rössler1 45

Finland

Early Modern Swedish

● 1555 Kunnars (gen) Audén1980 p. 165

France

Latin

● c823 Guntarius (nom) irminon-vol2 35, Palatiolum, Gunterii (gen) ibid. 38, Wan, Guntharius (nom) ibid. 66; 1030 Gunterius (nom) StVdM-II 678; c1035 Gunterius (nom) ibid. 668; 1067x1086 Gunterio (dat) CartNDSaintes XIV; 1101x1129 Gunterius (nom) CartStPC XXXII; a1116 Gunterius (nom) ibid. XX; 1138x62 Gunterii (gen) clairvaux-12thc 74; 1138x1162 Gunterio (abl) ibid. 91; 1147 Gonterius (nom) ibid. 14, Gunterus (nom) ibid. 15; a1163 Gunterus (nom) ibid. 97; 1164 Gunterus (nom) ibid. 121; 1171 Gunterus (nom) ibid. 140; 1178 Gunteri (gen) ibid. 167; 1179 Guntero (abl) ibid. 178; 1301 Gonterus (nom) MemPic-vol17 p. 211

Old French

● 1296 Gontier paris1296 p. 32

Germany

Latin

● 822x875 Guntharius (nom) TradCorb §40; 1016 Guntherius (nom) UrkStyria 37; 1018 Guntherius (nom) quix-vol1 57; 1020 Cuntherius (nom) UrkStyria 40, Guntherius (nom) ibid. 39, quix-vol1 23; 1023 Guntherius (nom) UrkStyria 41; 1135 Gunterus (nom) quix-vol1 95; 1206 Guntherus (nom) hennes-vol1 7; 1207 Guntherus (nom) ibid. 8; 1212 Guntherus (nom) ibid. 12; 1230 Guntherus (nom) ibid. p. 91; 1234 Guntherus (nom) ibid. 91; 1426 Guntherum (acc) mairhofer DCCXXIII, Guntherus (nom) ibid. DCCXXIII

Italy

Latin

● 1226 Güntherus (nom) hennes-vol1 70

Poland

Latin

● 1228 Guntherus (nom) hennes-vol1 p. 81