The release of energy visible in the dark, caused by the presence of phosphorus chemical compounds, especially in Armillaria mellea (honey mushroom).

Foxfire is the term for the bioluminescence created by a fungus that can grow on decaying wood in the right conditions. It is often attributed to members of the genus Armillaria, though others are reported, and as many as 40 individual species have been identified. On the suggestion of Benjamin Franklin it was used for light in the Turtle, an early submarine.

Foxfire was a fictional character from Marvel Comics' original Squadron Supreme series. Unlike most of the Squadron's villains, she does not seem to have a DC Comics counterpart.

Foxfire is a 1996 movie based on the Joyce Carol Oates novel .