Bill

Bill is a character that first appeared in Pokémon Red and Blue.

Red, Blue and Yellow
Bill invented the Pokémon storage system and also helped create all of its successors. Bill also invented the Time Capsule found in the Johto region. In the Kanto-based games, Bill lives and works on Cerulean Cape and his family lives in Fuchsia City east of Koga's Gym.

FireRed and LeafGreen
Bill invites the player character to One Island to meet his friend Celio after you have gotten the Volcano Badge. In the Johto based games, he lives in Goldenrod City with his sister and mother, while his grandfather lives on Cerulean Cape. His Hoenn counterpart is Lanette and his Sinnoh counterpart is Bebe.

Gold, Silver, Crystal
Bill has some fans. One of them, Pokémaniac Brent in Generation II, will sometimes call the player character and tell him or her trivia about Bill. Some of the things he says is that Bill's mother was a Kimono Girl, his sister can't wink, and that Bill is lactose-intolerant.

Heart Gold and SoulSilver
In HGSS, Bill had the same role as that of Gold, Silver, and Crystal.

Season 1: Indigo League
In the anime, he was a researcher who lived in a lighthouse and needed to secure a place to sleep for Ash, Brock and Misty, per Professor Oak's favor. When the Mysterious Pokémon appeared, Bill and the others were happy to hear its voice, but after Team Rocket attacked, the Pokémon crashed the lighthouse and went away. Even if it disappeared, Bill still believed he would meet it once more.

Trivia
In Generation I there was a small gap in the back of Bill's house. However, the gap was removed in the other generations.

The character could be a reference to Bill Gates, as they share a first name and both invented a widely-used, important piece of computer technology.