Catherine was the daughter of Thomas Howard, the 2nd duke of Norfolk and Thomas' second wife, Agnes Tylney/Tilney. She is said to have been born at Ashewell, Thorpe, Norfolk, England, though her father's ducal castle was at Framingham, Suffolk, England. Her birth date of 1499 is a guess, based on known dates and historical events.
She married before 1522, as her 1st, to Rhys ap Gruffydd/Griffith (FitzUryan), son of Sir Grufudd ap Rhys and Catherine St. John. Her married name was Catherine Gruffydd, and they lived at Newton, Carmarthenshire, Wales, where Rhys was Mayor-Escheator of Carmarthen (1529-1530). He was beheaded for treason in 1531.
She married after 1533, as her 2nd, to Henry Daubeney, 1st and last Earl of Bridgwater, son of Giles Daubeney, 1st Baron Daubeney and Elizabeth Arundell. Catherine and Henry had no children. This marriage to Henry Daubeney apparently was not a happy one, as by 1535, he was asking for a divorce.
↑ 3.03.13.2 Wikipedia Contributors, Thomas Howard, 2nd Duke of Norfolk citing Richardson, Douglas (2004). Plantagenet Ancestry: A Study in Colonial and Medieval Families, ed. Kimball G. Everingham, among others, 7 September 2014, accessed November 22, 2014