Michael Carter, a historian at English Heritage, an organization that manages more than 400 historic buildings, found the objects listed on a 580-year-old inventory for Battle Abbey in Sussex, southeast England.
Highlights from the list of 175 individual objects include a hair shirt and finger bone believed to have belonged to St. Nicholas -- better known as Santa Claus -- and relics from Christ's birthplace.
The relic inventory is one of roughly 30 to have survived from medieval England.
William the Conqueror, who seized the English throne by winning the Battle of Hastings in 1066, is believed to have built Battle Abbey on the site of his victory over Harold II, the Anglo-Saxon king.
Among other objects, William the Conqueror is thought to have gifted relics of several of the Holy Innocents -- infant boys slaughtered in Bethlehem on the orders of King Herod -- to the monastery, according to a statement from English Heritage.
The organization also said William the Conqueror was a "notorious Scrooge" when it came to making gifts English abbeys -- but that Battle Abbey was an exception.
Another royal gift was presented to the monks of the abbey in 1200, when King John -- who was later forced to sign the Magna Carta charter of rights -- gave them relics believed to be from Christ's tomb and his "True Cross."
Carter said he was thrilled to think he might be the first person in half a millennium to comprehensively study the "glorious list" from Battle Abbey.
"It's fascinating how connections to our Christmas today, can be traced back almost a thousand years and despite Henry VIII's violent suppression (of the monasteries during the English Reformation), these great monasteries are still giving up their secrets", Carter added.
His research is published in the December issue of The Journal of Medieval Monastic Studies.
The relics manuscript is housed in the Huntington collection in California.