Huey, Dewey, and Louie are virtually identical to one another except for the color of their clothes. They are a trio of small, anthropomorphized ducks with amber-coloured beaks, legs, and webbed feet, four-fingered hands, white plumage, thin, grey "eyebrows", and light blue eyes that almost seem to glow. Each wears a long-sleeved turtleneck shirt and baseball cap. Huey's cap and shirt are red, Dewey's are blue, and Louie's are green.
Despite being depicted as kids in Kingdom Hearts, the trio still exist ten years in the past (during the events of Kingdom Hearts Birth by Sleep), living in Disney Town. This suggests that they may be older than they look or the flow of time is different in Disney Town.
The trio appears in Disney Town participating in the world's mini games. They are having trouble handling the ice-cream machine when Ventus arrives, but they manage to make it work properly with his help. With the restored ice cream machine, they make the special ice cream for the Million Dreams Award. During the ending credits, the trio race on the Rumble Race ground, with Huey as the victor.
Judging by conversations with the three in Traverse Town in the item shop, one can clarify that the three brothers went off to seek their fortune. They tell Donald that they wished to make money so they went off to start their shop. During the ending credits, they are seen returning to Disney Castle.
They also appear selling items in their shops, but this time in Hollow Bastion and each of them have their own shops. During the ending credits, they return to Disney Castle along with King Mickey, Goofy, Donald, Scrooge, Jiminy Cricket and Pluto.
Huey, Dewey and Louie now reside in Twilight Town where they are the main workers of the Gummi shop, a shop that allows Sora, Donald and Goofy to buy new versions and/or materials for their Gummi ship. Their shop brings in newer materials and upgraded versions of the Gummi ship all throughout the story, and can also be accessed for shopping via the world map. Their shop is located right in front of their uncle Scrooge's Le Bistro Grand restaurant, and they can also speak to you with some brief conversations when visiting their store in Twilight Town.
In Kingdom Hearts, Huey, Dewey and Louie take turns being the shop barter in the Item Shop in Traverse Town. In Kingdom Hearts II, Huey is in charge of the Accessory Shop, Dewey is in charge of the Items Shop and Louie is in charge of the Weapons Shop in Hollow Bastion/Radiant Garden.
Huey, Dewey and Louie make their first appearance in the 1938 short titled Donald's Nephews.
Strangely, it's not ever shown how Huey, Dewey, and Louie ever got to Traverse Town if Disney Castle wasn't destroyed. Plus, it's unknown why they wouldn't be at Disney Castle in Kingdom Hearts II, but instead at Hollow Bastion, yet they do tell Ventus that they're going to save up Munny to go on a big adventure.
In Kingdom Hearts Birth by Sleep, being a story from various years ago, Huey, Dewey, and Louie should have appeared being babies.
Kingdom Hearts 3 marks Huey, Dewey and Louie's voice actress Russi Taylor's final video game performance after her passing in July, 2019.