The Istvaeones (also called Istaevones, Istriaones, Istriones, Sthraones, Thracones, Rhine Germans or Weser-Rhine Germans (Istwäonen, Weser-Rhein-Germanen in German)) were a West Germanic cultural group or proto-tribe. Their name comes from Tacitus’ Germania (c. 98 CE) who categorized them as one of the tribes of Mannus and labelled them as those tribes who were not either Ingvaeones or Irminones. They dwelt around the Atlantic coast (modern day Netherlands, Belgium and northern France) as well as the Rhine and Weser river systems from perhaps 500 or 1000 BCE, until the differentiation of localized Teutonic tribes (Chatti, Hessians, Franks) in that region circa 250 CE. There is also evidence some of them merged with the North Sea Germans (Ingvaeones).

Jakob Grimm in his Teutonic Mythology urged that Iscaevones was the correct form, partly because it would connect the name to an ancestor figure in Norse mythology named Ask, partly because in Nennius where the name Mannus is corrupted as Alanus, the ancestor of the Istaevones appears as Escio or Hisicion. There the sons of this figure are, fantastically, from Frankish tradition, Francus, Romanus, Alamanus, and Bruttus, the supposed ancestors of the Franks, Latins, Germans and Britons. This seems to reflect Frankish desire to connect the Franks with the people they ruled.