FES or Fes may refer to:

• Fès or Fez, a city in Morocco
• Fès Roland & Fès Begon, or Fez Roland & Fez Begon, hamlets of Moissac-Vallée-Française, canton of Saint-Germain-de-Calberte, arrondissement of Florac, department of Lozère, France (maybe remembering a battle of Pepin the Short against Septimania located Muslims).
• Feline sarcoma oncogene, a human gene that encodes the feline sarcoma oncogene enzyme
• FES (Ayase Kishimoto), a fictional singer from Chaos;Head anime series and alias of Yui Sakakibara for her songs from Chaos;Head and Steins;Gate anime series
• The Famous Entrepreneurs Series, a business membership club
• Flywheel energy storage, an energy storage method
• Friedrich Ebert Foundation (German: Friedrich Ebert Stiftung)
• Forschung und Entwicklung von Sportgeraten
• , the special forces of the Mexican Navy
• Functional electrical stimulation, a neurological treatment technique
• Iron(II) sulfide or FeS, a chemical compound
• Persona 3 FES, an add-on disk for Shin Megami Tensei: Persona 3
• Fat Embolism Syndrome, a disease caused by fat emboli arising from fractured bones.
• Flat Earth Society, a group that believes the Earth is flat.
• Facultad de Estudios Superiores, National Autonomous University of Mexico faculties

Fez (French: Fès; ; Berber: Fas, ⴼⴰⵙ) is the second largest city of Morocco, with a population of 1.1 million (2014).

Iron(II) sulfide or ferrous sulfide (Br.E. sulphide) is a chemical compound with the formula . In practice, iron sulfides are often iron-deficient non-stoichiometric. Powdered iron sulfide is pyrophoric (ignites spontaneously in air).