The land around Middleham was given to Alan The Red. Alan built a wooden motte-and-bailey castle, 500 yards to the south-west of where the present castle stands, on a site known as William’s Hill. It can be seen from the current keep. It was built to guard Coverdale and to protect the road from Richmond to Skipton.

By the time of the Domesday Book in 1086 Middleham had been granted to Alan the Red’s brother Ribald. Two generations later Alan’s grandson, Robert FitzRibald built a new castle which featured a massive stone keep . The keep, one of the largest in England, had twelve-foot thick walls and three floors; for its time, this would have provided palatial accommodation. It contained a great chamber, large kitchen, chapel, dovecot, cellars and the living rooms of the lord of Middleham.  No wonder it was so popular with one of its later inhabitants – The Duke of Gloucester a.k.a. Richard III.  The castle came to be known as The Windsor of the North.

But what of Ribald?  He appears to have been born circa 1050 and died in 1121 in St Mary’s Abbey York where he had withdrawn after the death of his wife, Beatrix de Tallebois in 1110.  He lived the final years of his life as a monk in Benedictine habits – hence the illustration. His lands, and he benefitted from being Alan’s brother – click on the image to see a list of lands he owned at the time of the Domesday Book- were passed to his son Ralph FitzRibald.  Four generations later the family line ended but not before the daughters of the family had married into the Percy and Bigod families.

Incidentally, the word ‘ribald’ referring to a coarse or vulgar person doesn’t make an appearance in the language until the thirteenth century and it came from the French word ‘riber’ meaning to live licentiously; it seems to have almost referred to a certain kind of henchman when it was first used.

 Ribald was almost a class name in the feudal system . .
      . He was his patron's parasite, bulldog, and tool . . .
      It is not to be wondered at that the word rapidly
      became a synonym for everything ruffianly and brutal.
                                               --Earle.
http://www.hyperdictionary.com/dictionary/ribald

Sadly, my Oxford Dictionary of Baby names doesn't offer any 
clue as to the origins or meaning of the name Ribald.