The B4419 is a road in two halves in North Wales. It is described in the 1922 Road Lists as Carnarvon - Llangaffo - Pentre-berw, crossing the Menai Strait via a ferry that was discontinued in the 1950s, thus leaving two unconnected sections which remain to this day. The ferry was only really suitable for foot passengers, which raises the question of why the road was numbered as a through route; the A5 was always the main road on and off the island.
As such, B4419 may refer to:
- B4419 (Anglesey), the majority of the original B4419 on Anglesey
- B4419 (Caernarfon), the southernmost section, left behind in the centre of Caernarfon