Cuthbert, for whom the Guild is named, was an English bishop in the 7th century. He is known as "Saint Cuthbert Incorrupt" becuase his body was said not to decay after his death in 687. During the Saxon invasions of England, the people would exhume his body whenever his resting place was threatened by battle, and would march across the countryside until reaching the next perceived resting place. {The Guild, whose primary function at Renaissance Faires is marching in parades, is thus aptly named.}

Cuthbert was finally interred in the Cathedral in Durham in the year 999. The last verified exhumation of his incorrupt body was by three commissioners of Henry VIII in 1537. His grave remains at Durham to this day. If you are interested in some images from there, try perusing the Guild's Images of the Saint.

Cuthbert was born in Northumbria around the year 630, and grew up as shepherd, but entered into monastic life early, according to Bede. He was said to have command of the winds and weather, and to be appointed by God to his Bishopric, and to have brought on many miracles.

Cuthbert was one evening praying by the ocean, and the waters rose up and overtook him. The next day he was washed ashore chilled, but still praising God. Then sea otters came, and warmed him, and comforted him, and washed his feet; and he gave them his blessing. Thus the Guild honors otters above all others of God's creatures.

Cuthbert was once walking with an attendant, and when they became hungry, he told his attendant to have faith in God, for God would find the means to provide them food. Sure enough, an eagle came, and caught a fish, and delivered it to them, proving the Saint's words correct.

St Cuthbert's Day is 20 March, five days before Lady Day, which was the traditional start of the calendar year, in Renaissance England.

The most famous, though by no means the only, biography of Cuthbert is that written by the venerable Bede. You can find the complete text of Bede's Cuthbert, together with a decent preface with some background, at the Medieval Sourcebook's HTML version of Bede's The Life and Miracles of St. Cuthbert, Bishop of Lindesfarne.