Milecastle 2 (Walker) was a milecastle of the Roman Hadrian's Wall. No remains are currently visible, having been built over, but its probable location is at or near the junction of the A187 Fossway and Tunstall Avenue, in the parish of Wallsend.

A milecastle was a small fort (fortlet), a rectangular fortification built during the period of the Roman Empire. They were placed at intervals of approximately one Roman mile along several major frontiers, for example Hadrian's Wall in Great Britain, hence the name.