A. niger

A. niger may refer to:
 * Acromyrmex niger, an ant species found in southern Brazil and Paraguay
 * Agelastes niger, the black guineafowl, a bird species found in humid forests of Central Africa
 * Allocyttus niger, the black oreo, a fish species found around Australia and New Zealand
 * Andricus niger, a gall wasp species in the genus Andricus
 * Aspergillus niger, the black mold, a fungus species