泛日耳曼主义是19世纪于德国流行的一种极端民族主义。

德意志帝国境内以日耳曼族为多数，少数斯拉夫人和犹太人。德意志帝国政府于普法战争后害怕法国会出兵报复，于是和其他欧洲国家结盟，以在外交上孤立法国。由于奥地利人和德国人同族，德意志帝国政府积极拉拢奥匈帝国与其结盟，为此推行泛日耳曼主义，大打民族牌。

Pan-Germanism (German:Pangermanismus or Alldeutsche Bewegung) is a pan-nationalist political idea. Pan-Germanists originally sought to unify all the German-speaking populations of Europe in a single nation-state known as Greater Germany.

Pan-Germanism was highly influential in German politics in the 19th century during the unification of Germany when the German Empire was proclaimed in as a nation-state in 1871 without Austria (Kleindeutsche Lösung/Lesser Germany), and the first half of the 20th century in the Austro-Hungarian Empire and the German Empire. From the late 19th century, many Pan-Germanist thinkers, since 1891 organized in the Pan-German League, had adopted openly ethnocentric and racist ideologies, and ultimately gave rise to the foreign policy Heim ins Reich pursued by Nazi Germany under Adolf Hitler from 1938, one of the primary factors leading to the outbreak of World War II. As a result of the disaster of World War II, Pan-Germanism was mostly seen as a taboo ideology in the postwar period in both West and East Germany. Today, Pan-Germanism is mostly limited to some nationalist groups in Germany and Austria.