Llantilio Crossenny is a small village and much larger former community, now in the community of Whitecastle, in Monmouthshire, south east Wales, in the United Kingdom. It is situated between the two towns of Abergavenny and Monmouth on the B4233 road. The community included Penrhos, and Llanvihangel-Ystern-Llewern.

Dafydd ap Llewelyn ap Hywel, better known as Dafydd Gam, anglicized to David or Davy Gam, was a Welsh warrior, a prominent opponent of Owain Glyndŵr. He died at the Battle of Agincourt fighting for Henry V, King of England in that victory against the French.