Alan Rufus, alternatively Alanus Rufus (Latin), Alan ar Rouz (Breton), Alain le Roux (French) or Alan the Red (c. 1040 – 1093), 1st Lord of Richmond, was a Breton nobleman, kinsman and companion of William the Conqueror (Duke William II of Normandy) during the Norman Conquest of England. He was the second son of Eozen Penteur (also known as Eudon, Eudo or Odo, Count of Penthièvre) by Orguen Kernev (also known as Agnes of Cornouaille). William the Conqueror granted Alan Rufus a significant English fief, later known as the Honour of Richmond, in about 1071.

Alan Rufus is first mentioned as a witness (along with his mother Orguen and brothers Gausfridus, Willelmus, Rotbertus, Ricardus) to a charter dated to 1056/1060, issued by his father Eozen to the Abbey of Saint-Aubin in Angers (q.v. Albinus of Angers).

Alan already held some property in Rouen, the capital of Normandy, and was lord of Richemont in Upper Normandy before September 1066. In 1066 or 1067, William of Normandy assented to the gift by Alan Comes (i.e. Alan Rufus) to St-Ouen de Rouen of the church of Saint-Sauveur without Rouen, and of the nearby church of Sainte Croix des Pelletiers, which had been his gift to Alan.

Alan was probably present at the Battle of Hastings in October 1066. On the journey to the battle site near Hastings, the Breton forces formed the vanguard, arriving a good half-hour before the rest of William's army. In the battle formation, Bretons are mentioned variously as in the left-wing or in the rear-guard of the army. Geoffrey Gaimar's L'Estoire des Engles and Wace's Roman de Rou both assert Alan Rufus's presence as Breton commander in the battle, and praise his contribution: Gaimar says "Alan and his men struck well" and Wace states that they did the English "great damage".

A column of Norman cavalry swept into the Cambridge area in late 1066 and built a castle on the hill just north of the river crossing. Alan's first possessions in England were in Cambridgeshire, so he may have obtained them about this time. The Cambridgeshire town of Bourn, west of Cambridge and due north of London, along with several other towns in the area were according to the Domesday Book held in 1066 by the royal thane Almer of Bourn as a tenant of Edith the Fair. Alan's early acquisitions in England included many land titles that had been in the possession of King Harold's wife Edith the Fair, including all but one of her holdings in Cambridgeshire.) Alan later favored Almer by giving him two additional manors.

In 1067, Alan witnessed a charter of King William to the monks of St Peter's at Westminster.

In January 1069, Earl Edwin in Yorkshire and his brother Earl Morcar in Northumberland rebelled. In late 1069, the King brought an army north to combat the rebels and recover York. According to the Register of Richmond, it was at the instigation of Queen Matilda, during the Siege of York, that King William conceded to Alan the Honour of Richmond (the Hundred of the "Land of Count Alan" in Yorkshire) in North Yorkshire. Unusually, within the land of Count Alan, King William himself and his half-brother Robert, Count of Mortain received only one manor each: William sharing one with Alan at Ainderby Steeple, on the eastern fringe of the Land, while Robert held one on its southern edge. The wording of the proclamation is:

Ego Wil(el)mus cognomine Bastardus Rex Anglie do et concedo tibi Nepoti meo Alano Britannie Comiti et heredibus tuis imperpetuum omnes uillas et terras que nuper fuerunt Comitis Edwyni in Eboraschira cum feodis Militum et ecclesiis et aliis libertat(ibus) et consuetudinibus ita libere et honorifice sicut idem Edwinus ea tenuit. Dat(um) in obsidione coram Ciuitate Ebor(aci).