Henry I De Percy
Henry I was born about 1156 in Whityby, Yorkshire, England.  He died before September 29th, 1198 in Cleveland, Yorkshire, England.

 Isabel De Brus
Isabel was born in Skelton, Yorkshire, England.  She died after 1230.

 William De Percy
William was born in Alnwick, Northumberland, England.  He died about July 28th, 1245.