The Eichelnkopf is a 545.7 m high hill in the southwestern part of the Harz Mountains in the central German state of Lower Saxony. The Eichelnkopf lies about 3.5 km east of Herzberg am Harz, about 3.5 km north of Scharzfeld and about 2.5 km southwest of the Großer Knollen. Its nearest neighbour is the Mittelecke. The hill is completely forested.
There is a trail that runs from the north and over the summit. The last 300 m below the summit, with an incline of up to 34%, is especially challenging for mountain bikers. On the south slope of the Eichelnkopf, a trail runs past the 300-year old "Owl Oak" (Euleneiche).