Styrum (German pronunciation: [ˈʃtiːʁʊm]; sometimes spelled "Stirum") was an immediate lordship in the Holy Roman Empire, located in Mülheim an der Ruhr, North Rhine-Westphalia, Germany.
After the murder of the Archbishop of Cologne, Engelbert of Berg, in 1225, the descendants of Frederick I of Isenberg gained ownership of Mülheim on the river Ruhr and thereby of the castle Styrum and the castle Hohenlimburg on the river Lenne.
Styrum was rebuilt in Baroque style in 1668, and it received its present form after a fire in 1738.
The community of Styrum is now part of the cities of Mülheim an der Ruhr and Oberhausen.
The name "Styrum" originates from "Stiarhem", meaning "Bulls Home" in the early medieval local dialect.