The Forest Ancient was an Ancient that could be encountered in God of War (2018) and in God of War Ragnarök as an optional boss.
God of War (2018)[]
After Kratos and Atreus left Fafnir's storeroom after completing the favor Fafnir's Hoard, a forest ancient can be seen wandering around outside the storeroom. Kratos and Atreus are given the choice to kill it or simply leave it alone. If Kratos attacks the ancient then a fight will ensue in which they have to kill it.
God of War Ragnarök[]
During the sixth chapter of the game The Reckoning, another forest ancient can be encountered at an abandoned village, which is right next to Freyr's Camp in Vanaheim. Just like in the previous game, it can be found wandering and ignoring Kratos until it is attacked.