Lyderhorn is a mountain in the city of Bergen in Vestland county, Norway.

It is located by Liavatnet approximately 5 kilometres (3.1 mi) west of the city center.

Due to its prominent visibility from the seas, it has historically been a navigational mark for sailors.

North of Ørnafjellet is Kvarven fort, a strategic point during World War II, still featuring several bunkers and cannon positions used in the defense of Bergen.

Lyderhorn, Ørnafjellet and Kvarven are popular hiking areas.