Oh, no! I need Luigi for a very important experiment! To go buy milk…
|—E. Gadd, Ssenmodnar 9|
He is a small and old experienced researcher with knowledge in various domains, especially the paranormal, who can help Luigi and Mario with his knowledge. In SMG4's canon, he appeared in a few bloopers. He is very smart with machinery, as his inventions have been the cause of a plot every once in a while, however, he can also be very foolish, just like the rest of the cast. It's revealed he often needs Luigi to do experiments or small tasks for him, although Luigi himself has almost never talked about doing this.
E. Gadd is short, wears huge glasses and a lab coat, a bucktooth, and only one curl of gray hair.
- High ingenuity: E. Gadd has a great talent for inventing things.
- His name "E. Gadd" is misspelled as "E gad" (with only one d instead of two) in the episode "Time Travel Tells".
- It's revealed in Ssenmodnar 11 that he has a YouTube channel. It currently has 21,000 subscribers.
- He is Rosalina's secret admirer.
- An airplane once crashed into his workshop, after Mario sent Fishy Boopkins flying with a slingshot.
- He is revealed to own a shop in SMG4: War On Smash Bros Ultimate.
- He turned Shroomy into a robot.
- In real Mario games, he appears in the series Luigi's Mansion and in the two first games of the Mario & Luigi series (Superstar Saga and Partners in Time).
- He was one of the rappers in War Of The Fat Italians 2017. He chose to support SMG4. During the rap, Mario called him "a wannabe-Edison."
- Professor E. Gadd was ranked as the 6th powerful "C-Tier" character in the "SMG4 Characters Powerlevels" tier list (following Rob the Scarecrow, Sonic the Hedgehog, Toad, Frankie, & JubJub Boopkins) during the 5,100,000 Subscribers Livestream.