Susan Test was a super genius girl. She was one of Johnny's sisters, Hugh and Lila's daughter, and Gil Nexdor's girlfriend. She was voiced by Marydike Hendrikse.
Susan has straight long red hair and she has navy blue eyes. She was seen wearing a light gray jacket, a light blue shirt, a black skirt, glasses, a yellow star shaped barrete, light gray socks, and black shoes. Her swimwear was a greenish blue one piece bathing suit. And her disco outfit was a greenish blue tank top, a black skirt, a greenish blue cap, bright greenish blue socks, and dark pink shoes.
- Sleepwear - Light blue pajamas with navy blue star symbols.
- Alternate sleepwear - Navy blue pajamas with bright yellow star symbols.
- Western outfit - Bright blue t shirt with light gray sleeves, light blue skirt, light gray socks, and black shoes.
- Early 50s outfit - Bright blue t shirt, light gray bandana, light gray poodle skirt, light gray socks, and black shoes.