Kingdom: Animalia
To be considered part of the kingdom Animalia the organisms must be heterotrophic, or consume their food instead of producing it. Other characteristics present in the Animilia kingdom are multicellularity, mobility, and a lack of a structural cell wall.  

The kingdom Animalia encompasses so many organisms, here are a few more: Damselfly, Mute Swan, and The North American Beaver

Phylum: Chordata
Chordates are deuterostomes, which means the anus develops before the mouth. To be a member of the phyla chordata a dorsal hallow nerve chord must be present; there must also be a tail extruding beyond the anus and pharyngeal gill slits.  

Other chordates include: Yellow Perch, Timber Rattlesnake, and the Green Frog

Class: Aves
Aves, more commonly known as birds, have a very unique set of characteristics which evolutionarily helped with the ability to fly. To highlight a few, Aves are warm blooded, have lightweight or hollow bones, and feathers.

Below is a phylogenic tree of the Aves class. Even within this group there is still a lot of diversity. The Harpy Eagle would be located near the bottom of the tree, under the Falcons tip, which would continue to break down into more closly related organisms. 

If the Aves Class interests you, here are a few more interesting organisms: The Green Heron, American White Pelican, or the Barred Owl  

Order: Falconiformes
Falconiformes are diurnal birds, meaning they sleep at night and maintain activity such as hunting during the day.  

Family: Accipitridae
Eagles and other members of the Accipitridae family are carnivorous birds. Evolution favored powerful wings for long distance flight and powerful claws for capturing and devouring prey.  

A closley related organism to the Harpy Eagle that shares its same family is the Red-tailed Hawk, check it out!

Genus: Harpia
Harpy Eagles have the largest body and talon size of all species of eagles.   

Species: Harpia harpyja
Also referred to as the American Harpy Eagle, can commonly be found in tropical South America. Their feather pattern presents itself in varying shades of grey and black with very distinct feathers on the back of its head. Harpy Eagles primarily consume small to medium sized mammals like sloths or monkeys.