Walter I de Claville (floruit 1086) ("alias" de Clarville and Latinised to "de Clavilla") was an Anglo-Norman magnate and one of the 52 Devon Domesday Book tenants-in-chief of King William the Conqueror.
 He also held lands in Dorset.
 His Devonshire estates later formed part of the feudal barony of Gloucester.
William I (c. 1028 – 9 September 1087), usually known as William the Conqueror and sometimes William the Bastard, was the first Norman King of England, reigning from 1066 until his death in 1087.
 A descendant of Rollo, he was Duke of Normandy (as Duke William II) from 1035 onward.
 After a long struggle to establish his power, by 1060 his hold on Normandy was secure, and he launched the Norman conquest of England six years later.
 The rest of his life was marked by struggles to consolidate his hold over England and his continental lands and by difficulties with his eldest son.
Alfred the Breton (fl.1086) (Latinized to "Alvred Brito") was one of the Devon Domesday Book tenants-in-chief of King William the Conqueror.
 He had 22 landholdings in the county of Devonshire held in-chief according to the Domesday Book of 1086, and held further lands as a mesne tenant, including the manor of Panson in the parish of St Giles-in-the-Heath.
 His manors later descended to the feudal barony of Plympton.
Gotshelm (floruit 1086) was an Anglo-Norman magnate and one of the 52 Devon Domesday Book tenants-in-chief of King William the Conqueror and was also a Cornwall Domesday Book tenant-in-chief.
 He is listed in the Domesday Book of 1086 as holding 28 estates or manors in Devon from the king.
 His brother was Walter de Claville (floruit 1086), also a Devon Domesday Book tenant-in-chief, who held 32 estates or manors in Devon from the king.
Baldwin FitzGilbert (died 1090) ("alias" Baldwin the Sheriff, Baldwin of Exeter, Baldwin de Meulles/Moels and Baldwin du Sap) was an Anglo-Norman magnate and one of the 52 Devon Domesday Book tenants-in-chief of King William the Conqueror.
Ansger (fl.
 1086) of Montacute was one of the Devon Domesday Book tenants-in-chief of King William the Conqueror.
Ralph de Pomeroy (died pre-1100) ("alias" de la Pomeroy, Pomeraie, Pomerei, etc.) was one of the 52 Devon Domesday Book tenants-in-chief of King William the Conqueror and was the first feudal baron of Berry Pomeroy in Devon.
 He held 58 landholdings in Devon.
The "Domesday Book" of 1086 lists in the following order the tenants-in-chief in Cornwall of King William the Conqueror:
Theobald FitzBerner (fl.1086), (Anglicised to Theobald son of Berner, Latinized to "Tetbaldus Filius Bernerius") was an Anglo-Norman warrior and magnate, one of the Devon Domesday Book tenants-in-chief of King William the Conqueror.
 The Domesday Book of 1086 lists him as the holder of 27 manors in Devon.
Robert of Aumale (fl.
 1086) (alias "d'Amarell, Damarell", etc., Latinised to "de Albemarle", "de Albamara", etc. ) was one of the Devon Domesday Book tenants-in-chief of King William the Conqueror (1066-1087).
 His lands, comprising 17 entries in the Domesday Book of 1086, later formed part of the very large Feudal barony of Plympton, whose later barons were the Courtenay family, Earls of Devon.

Question: What is Cornwall Domesday Book tenants-in-chief: about who died in 1087?
Answer: William the Conqueror