萘（Naphthalene），是一种稠环芳香烃。萘，音「耐」（汉语拼音：nài，注音：ㄋㄞˋ）。

可从煤焦油分离和石油重整制得。

Naphthalene is an organic compound with formula C
10H
8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.