Luigi

Luigi finally made his first appearance in an episode of Everytale, being Everytale S4E?: Zoom. However, even before his first appearance, his name was listed in the end credits, so he did canonically exist within the Everytale universe before that episode aired. Mario and Luigi are brothers, just like in the games. His first appearance was in The Night Club S1E1: The First Episode, and has appeared in every episode of The Night Club to date.

Notable Appearances
Everytale S4E?: Zoom: First appearance

Character Progression
No character progression

Other Appearances
He has briefly appeared in several episodes of Pikmin, usually to fix the plumbing.