Styrum (sometimes spelled "Stirum") is a castle in Mülheim an der Ruhr in North Rhine-Westphalia, Germany. It is unknown when Styrum was built, but Styrum was already prosperous in Frankish times before Charlemagne (reigned 771 - 814). In 1067 Styrum was given to the Abbacy of Kaiserswerth. After the murder of the Archbishop of Cologne, Engelbert of Berg, in 1225, the descendants of Frederick I of Isenberg gained ownership of the castle as Lords of Styrum and took up residence. Here they founded the line of Counts of Limburg-Styrum, a family that would later obtain important estates in Westphalia and the Lower Rhine. With the partition of the House of Limburg-Styrum in 1644, Styrum passed to the line of Limburg-Styrum-Styrum.
Styrum was rebuilt in Baroque style in 1668, and it received its present form after a fire in 1738. In the mediatisation of 1806, Styrum came under control of the Grand Duchy of Berg. The line of Limburg-Styrum-Styrum became extinct in 1808. Styrum was purchased by the German industrialist August Thyssen in 1890. His company gave the castle to the city of Mülheim in 1960. It was transformed into a restaurant, artist studio and community centre for the elderly in 1992.
The name "Styrum" originates from "Stiarhem", meaning "Bulls Home" in the early medieval local dialect.