A. audax may refer to:

• Abacetus audax, a ground beetle found in Chad and Côte d'Ivoire
• Acentrogobius audax, a goby found in the coasts of the Indian and western Pacific Oceans
• Agrilus audax, a jewel beetle found in North America
• Allotinus audax, a synonym of Allotinus fallax, a butterfly found in Asia
• Aphanotriccus audax, the black-billed flycatcher, a bird found in Colombia and Panama
• Aquila audax, the wedge-tailed eagle, a bird found in Australia
• Archips audax, a moth found in Japan
• Attus audax, a synonym of Phidippus audax, the bold jumping spider, native to North America