Fornham St Martin is a village and civil parish in the St. Edmundsbury District of Suffolk in eastern England. Located on the northern outskirts of Bury St Edmunds to the east and west of the A134, in 2005 its population was estimated at 1300. Its modern parish council is shared with neighbouring Fornham St. Genevieve, and is known as Fornham St Martin cum St Genevieve Parish Council.
Once having a reputation for "pie-ladies" – women who walked to the abbey in Bury St Edmunds to feed the monks – today it is dominated by modern housing.
The name "Fornham" is thought to be Saxon meaning "The homestead by the trout stream" and the village is well documented in the Domesday Book of 1086.
The Battle of Fornham, one of the most significant battles in English history took place in Fornham Park and the surrounding area in 1173. Scribes of the time variously estimated that between 3,000 and 10,000 Flemish mercenaries were slaughtered and lie beneath the fields, woodland and ditches.
The village appears on John Speed's 1610 map as "Fernham mertin" and in 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described the town as "a parish in Thingoe [registration] district, Suffolk in the Diocese of Ely; on the river Lark, 1¾ mile North of Bury St Edmunds" and related that "it had 74 houses, a post office, a church and a free school".