This article explores the connections between migration and foreign combat, offering an improved definition of „foreign fighters,” and a general concept of foreign combatants’ behaviour as an anomalous form of migration. In contrast with the popular discourse and terrorism-related concerns about present-day Western European foreign fighters in Iraq and Syria (and their return to Europe) and Middle Eastern migrant refugees (and their arrival in Europe), the intention of this article is to offer a conceptually thorough consideration of the causal connections between movements of migration and the presence of foreign combatants in armed conflict, informed by a wide sample of cases. Such an assessment has to take place with a view to all forms of migration (including forced migration), all forms of foreign combat (not only foreign combat on the side of non-state actors as David Malet's oft-cited but overly restrictive definition would imply), and regions of the world beyond the Middle East and Islamic countries. Along these guiding lines, the article points out many comparatively rarely considered cases of foreign combat as well as the underestimated obstacles in the way of fighting abroad. Taking account of the latter allows refutation of a key implication of „new war theory” (its focus on „greed” as a motive of combatants), in light of the continued importance of cultural factors and ideological motives for participation in foreign combat.