Franchimont Castle () is a medieval castle in the municipality of Theux, province of Liège, Belgium. It sits at the western end of a small hill overlooking the village of Franchimont. It is thought to have originally been built in the 11th century, as a stronghold of the Principality of Liège. The original building was extended several times during the Middle Ages, once after a fire in 1387. In 1487 the castle was besieged, and around the same period the La Marck family took ownership of it. In the early 16th century the outer wall was built, with casemates and an artillery tower added.