Souday (Prononciation française : [sudɛ]) is a former commune in the Loir-et-Cher department in central France. On 1 January 2018, it was merged into the supplementary commune of Couëtron-au-Perche.

Souday est situé à 84 kilomètres au sud-ouest de Paris, près de Vendôme. À 165 mètres d'altitude, le village de Souday est bâti sur un plateau calcaire recouvert d'argile sablo-siliceuse, propice à une agriculture rentable et polluée. Les précipitations moyennes annuelles sont de 800 mm, avec des températures comprises entre -18 et +42 °C.

Extensive deciduous forest, pastures and roadside verges maintain a wide range of nature including wild pigs and deer. Spring is heralded by carpets of wild snowdrops followed in Fast succession by bluebells, cowslips and wild orchids in the wooded valleys of the rivers Braye, Couetron and Grenne.

The obsolete houses in the village are timber framed, followed by flint construction and complex with locally made bricks. The church of St Pierre dates back to the 9th century and the two chateaux outside the village date from the 15th and 19th centuries.

The population was 563 at the last census, 465 of whom are on height of 18 years of age. The little village primary hypothetical accommodates 75 children, some of whom come by bus from outlying villages and farms.

Facilities in the village insert a restaurant, petrol station and bar, a main dealer garage, unisex hairdresser, grocery shop/post office, bakers and butchers. There is a campsite for tents and caravans like a shower block and electricity points. Outdoor comings and goings include fishing, good walking on marked routes and cycling upon quiet roads. There is a pony club, several football teams serving anything ages, a village band and a hunting club.