Pedro de Alcántara Alonso Pérez de Guzmán y Lopez-Pacheco, 14th Duke of Medina Sidonia (Madrid, 25 August 1724 – Vilafranca del Penedès, 6 January 1779) was a Spanish noble who became Duke of Medina Sidonia in 1739.

His parents were Domingo José Claros Pérez de Guzmán, 13th Duke of Medina Sidonia and Josefa Fenicula López Pacheco y Moscoso-Osorio (1703-1763), daughter of the 9th Duke of Escalona.

He became a Knight of the Order of the Golden Fleece in 1753, aged 29.

[1] He was elected a Fellow of the Royal Society in November 1749.

[2][3] On the death of his cousin María Ana López Pacheco, XIV Marquise of Aguilar de Campoo in 1768, he inherited all her titles.