Caill Tomair (Middle Irish 'Thor's Grove') was a sacred grove dedicated to the North Germanic god Thor. Located near the Norse-Gaelic city of Dublin, the grove was destroyed by forces led by Brian Boru early in the year 1000 AD.

According to scholar Poul Holm, the grove was likely targeted due to its role among the local population:

[Caill Tomair] must have been a sacred wood and was deliberately cut down by Brian Boru of Munster when he conquered the town at Christmas in the year 1000. The cutting was a considerable undertaking and may have been conducted to clear an open passage to the town as much as to undercut a pagan rite which by then must have been rapidly declining.^[1]