Eldjárn or Eldjarn is a surname. Notable people with the surname include:
Ari Eldjárn (born 1981), Icelandic comedian Halldóra Eldjárn (1923–2008), First Lady of Iceland, 1968–80 Kristján Eldjárn (1916–1982), President of Iceland, 1968–80 Lorentz Eldjarn (1920–2007), Norwegian biochemist Þórarinn Eldjárn (born 1949), Icelandic writer