The sylvaneth, sometimes called "Alarielle's Children," and once known as the Treemen of the World-That-Was, are a species of intelligent, usually humanoid tree spirits created by Alarielle, the goddess of life and nature.

The term "sylvaneth" encompasses a wide range of different tree-like humanoids first created when Alarielle planted seeds she had saved from the destruction of the World-That-Was in Ghyran during the Age of Myth.

Since then the sylvaneth have greatly multiplied, and while they remain at their strongest in their native Realm of Life, they have spread to the other Mortal Realms in the Age of Sigmar.