The Großer Knollen (or Groß Knollen) is a 688-metre (2,257 ft) high mountain in the southwestern part of the Harz in Lower Saxony, Germany. The Großer Knollen is located northeast of Herzberg am Harz and Scharzfeld, north of Bad Lauterberg im Harz and south of the hamlet of Sieber. It is surrounded by several other mountains and hills that range in height between 550 and 650 m above mean sea level. Just under 1 km away to the southwest the Kleiner Knollen rises to a height of 631 m.
From the roughly 20 m high observation tower, which stands next to the inn on the summit of the Großer Knollen, there is a view not only over the mountain peaks of the Harz, but also southwards to the Rotenberg and Eichsfeld. In good conditions visitors can even see as far as the Thuringian Forest to the south.