Viker is a parish in the historical province of Västmanland and in present Nora Municipality, Örebro County, Sweden.
Viker is situated in Nora Municipality's southwestern corner in the central part of Örebro County.
The lakes Vikern (only partly in Viker), Älvlången, Malmlången (part of Svartälven) and Hovmanstorpsjön are situated in Viker.
Beteshult in the southern part of Viker is the highest point of the area with 253 meters above sea level.
The area has had an extensive iron industry with several mines and blast furnaces.