|Alias||Captain Spring Green|
|Relatives|| Gladys (mother)|
Nergal Jr. (cousin)
Harold's father (paternal grandfather)
Jeff the Spider ("son")
King of Asgard
|Real world information|
|Appears in|| Grim & Evil|
The Grim Adventures of Billy & Mandy
|First appearance||"Meet the Reaper"|
|Voice actor||Richard Steven Horvitz|
Billy is the main protagonist of the series. He is a dimwitted happy-go-lucky boy with a large pink nose. He only appears in The Grim Adventures of Billy and Mandy and its spinoff, The Grim Adventures with Billy, Mandy, Felicity and Toby.
- After The Grim Adventures of Billy and Mandy got cancelled, Maxwell Atoms ran out of ideas so Billy decided to appear on The Grim Adventures with Billy, Mandy, Felicity and Toby.