The Duke of Medinaceli is a Spanish noble title that originated in the 15th century. It was granted to the House of Medinaceli, a prominent family with significant influence in Spanish history. The title is associated with the town of Medinaceli in the province of Soria, Spain. The Duke of Medinaceli has held various privileges and responsibilities over the centuries, including governance of lands and participation in the Spanish court. The title is still active today, with the current duke being a member of the Spanish nobility and involved in cultural and charitable activities.