Xylaria is a genus of ascomycetous fungi commonly found growing on dead wood. The name comes from the Greek xýlon meaning wood (see xylem).

'Outline of Fungi and fungus-like taxa' by Wijayawardene et al. lists up to c. 571 species (in 2020), and around 454 records are listed by Species Fungorum (including synonyms).

Two of the common species of the genus are Xylaria hypoxylon and Xylaria polymorpha.

Xylaria hypoxylon, known by the common names stag's horn and candle-snuff fungus, is the most conspicuous because of its erect, 3–7 cm tall, antler-like ascocarps (fruitbodies) which are black at the base (where the perithecia are embedded) but white and branched towards the top, where the fruiting bodies produce white conidia (asexual spores).

Xylaria polymorpha, dead man's fingers, often grows in finger-like clusters from the base of a tree or from wood just below ground level. This is a primary fungus utilized in the spalting of sugar maple and other hardwoods.

Xylaria longipes, known by the common name dead moll's fingers, allegedly improves the quality of the wood used in string instruments. It has not been linked to spalting of maple.

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