Sometime in his youth he served in the galactic army until he met his future wife, whom proposed to him and the two got married and had at least one daughter: Nora Andromedos. After retiring from whatever profession he worked in, Leo stayed at the Old Folks Retirement Planet.
Leo is a kind, caring but sometimes cranky old man who often keeps in touch with his family. Leo is very close to his grandson Lloyd, who in turn looks up to him like a sort of father figure. Leo has a weakness for not being able to talk to the opposite sex very well, often stumbling and stuttering his words and running away, a trait that he passed down to Lloyd. Leo is shown to be quite intelligent, still knowing several ancient Verdigrian customs such as "Theerlap", the Verdigrian holiday.
- Nora Nebulon (daughter)
- Lloyd Nebulon (grandson)
- Francine Nebulon (granddaughter)
- Mrs. Andromedos (wife) [deceased]
- (To Lloyd) "Well heck Lloyd, you must feel like a freak!"
- "Don't tell Lloyd, okay? I've been trying real hard to make a good impression on him."