Katherine Howard (1525-42)
+ Joyce Culpeper (1482-1531)
+ Isabel Worsley (1450-1527)
+ Rose Trevor verch Edward (1422-1460)
+ Angharad Puleston (1392 Flintshire, Wales-1420) m. Edward Trevor ap Daffyd (1365 Denbighshire, Wales -1448)
+ Lowri ferch Gruffudd Fychan (b.1360) m. Robert Puleston (b.1358)
+ Elen ferch Thomas (b.1325) m. Gruffudd Fychan ap Gruffudd (b.1325)
+ Thomas ap Llewelyn (1302-43) m. Eleanor Goch
Owain (ap Gruffyd Fychan) Glendower, Prince of Wales (1349-1416), was the older brother of Katherine's ancestor Lowri ferch Gruffudd Fychan, and it was this Owain who led the rebellion against King Henry IV in 1400.
Owain and Lowri were maternal first cousins to Maredydd ap Tudur (d.1406), who along with his older brothers Rhys the Sheriff of Anglesey, and Gwilym, supported Owain's rebellion. Maredudd's mother Margaret ferch Thomas, and Lowri and Owain's mother Elen ferch Thomas were sisters. Therefore Katherine Howard's ancestry and her husband King Henry VIII's ancestry meet at Elen and Margaret's father Thomas ap Llewelyn, Lord of South Wales (1302-43). Maredydd, or Meredith in its anglicized form, was the father of the Owen Tudor who married Katherine of Valois and became the great-grandfather of King Henry VIII.
Lowri's husband Robert Puleston was a supporter of his brother-in-law Owain in the rebellion. As well as this, Lowri and Robert's son Roger (d.1469) was an ally of Jasper Tudor and was his Deputy Constable in the years 1460-1.