The classification of a lion in the Animalia kingdom is as follows:

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Carnivora
• Family: Felidae
• Genus: Panthera
• Species: Panthera leo

This classification places lions within the big cat family (Felidae) and the Panthera genus, which includes other large cats like tigers, leopards, and jaguars. The scientific name for the lion is Panthera leo.