Professor Elvin Gadd
“I'm getting too old for this ghost-catching tomfoolery.”
Professor E. Gadd, full name Professor Elvin Gadd (sometimes Dr. E. Gadd; Japanese: オヤ・マー博士 Doctor Oya Mā), is the scientist first appearing in Luigi's Mansion and founder of Gadd Science, Incorporated. He always speaks in ambiguous gibberish (supplied by Kazumi Totaka, who took inspiration from Animal Crossing's "Animalese" when inventing the voice). His name comes from the minced oath "egad," something that one says in amazement or shock.
The Mario Bros. go back in time and end up saving his lab from burning down when fire blocks erupted from the Thwomp Volcano. He then helps the Mario Bros. by inventing the Hydrogush 4000. Although he doesn't directly invent the Hydrogush 4000, his older self does in a complex way: Young E. Gadd starts to get an idea after a totally unrelated event happened during the present time, which transfers to his future self, causing the present-day, elderly professor to send water from the Hydrogush 4000 via Time Hole and calm the erupting Thwomp Volcano. After all this excitement, the twenty-year-old E. Gadd moves to Boo Woods.
 Luigi's Mansion
Many decades later, in Luigi's Mansion, Luigi enters the mansion and is saved from ghosts by a strange old man wielding a vacuum cleaner. Professor E. Gadd reveals he lives in a house near the mansion, where he researches his favorite subject: ghosts. Luigi explains his brother Mario is missing within the house, and the professor decides to help Luigi by giving him two of his inventions, the Poltergust 3000 and the Game Boy Horror. The professor continues to help Luigi throughout the game, giving him help and tips.
 Luigi's Mansion: Dark Moon
After a few years of absence, Professor E. Gadd appears in the game Luigi's Mansion: Dark Moon. In the game, E. Gadd takes up residence in Evershade Valley after learning that the ghosts there are friendly. Eager to examine ghosts without fear of being attacked by them, he sets up a laboratory in the Gloomy Manor and a Bunker close by the mansion. There, he begins researching the ghosts of the five mansions that populate the valley, and sends his five Toad assistants to the other four mansions in the valley to examine the ghosts there. At first, the resident ghosts welcome him and assist him in his lab, but when King Boo arrives and destroys the ghost-pacifying Dark Moon that hangs over Evershade Valley, the ghosts start running amok and destroy E. Gadd's equipment. He flees to his nearby Bunker and enlists the help of Luigi — who has now taken up residence in his new Grade D mansion from the previous game — to help rebuild the Dark Moon and calm the ghosts once more. E. Gadd was later revealed to have been unintentionally and indirectly responsible for King Boo's return, as he had sold his portrait in a garage sale, thus ensuring his escape.
In this game, E. Gadd has made an upgrade of his Poltergust 3000 from the last game: the Poltergust 5000. This new Poltergust uses a Strobulb to stun ghosts, rather than the flashlight used with the Poltergust 3000. Professor E. Gadd also introduces three new inventions: the Pixelator, a machine that turns Luigi into pixels and transports him to and from the different mansions, the Dual Scream, a device that resembles a Nintendo DS and is capable of communication, and the Dark-Light Device, which allows Luigi to see invisible objects.
 Super Mario series
 Super Mario Sunshine
Although Professor E. Gadd does not appear in Super Mario Sunshine, when Mario initially finds F.L.U.D.D. at the Delfino Airstrip, it says, "Thank you for purchasing this item from Gadd Science, Inc.". Later, Bowser Jr. says he got his Magic Paintbrush from "a strange old man in a white coat." This is a fitting description of Professor E. Gadd, which is further confirmed when F.L.U.D.D. seems to react in surprise to the statement. It is unknown if E. Gadd actually gave Bowser Jr. the paintbrush, or if Bowser Jr. stole it from him, though the latter theory is more likely. There is a symbol on both the Magic Paintbrush and F.L.U.D.D. showing a face and hairstyle similar to E. Gadd's, which seems to be the Gadd Science, Inc. logo. It appears on many of E. Gadd's other inventions, as well as the boxes for F.L.U.D.D.'s nozzle upgrades.
 Mario & Luigi series
 Mario & Luigi: Superstar Saga
In Mario & Luigi: Superstar Saga, the professor makes an appearance supplying the brothers with an array of accessories to help them along their way each time they drink at Starbeans Café, a coffeehouse that he owns. However, it has been found that originally, the game was only going to feature Professor E. Gadd once, the first time Mario and Luigi get a drink; in all of the future times, different characters would have appeared. These characters are Wario, Samus Aran, Fox McCloud, Link, an Excitebike racer, and Captain Olimar.
 Mario & Luigi: Partners in Time
In Mario & Luigi: Partners in Time, the professor debuts his newest invention to the Mushroom Kingdom, a Time Machine. Princess Peach, accompanied by Toadiko, and Toadbert, volunteers to be a passenger on its maiden voyage. However, when the time machine returns, it is not the trio that left but rather a strange creature that emerges instead. After the bros. defeat it, Gadd places the creature inside a tube of fluid, keeping it alive and allowing him to study it.
Out in the courtyard, Mario and Luigi discover a hole in the ground; E. Gadd elaborates that this hole is a Time Hole, a rip in the time-space continuum, which was created by the use of the time machine. After Luigi falls in the hole and Mario heads in to save him, the professor sends Stuffwell, a sentient suitcase, through to help them. For most of the rest of the game, E. Gadd is seen studying the Junior Shrooboid defeated earlier.
At Thwomp Volcano, Mario, Luigi, and their baby counterparts come across a younger Professer Gadd, who is studying Thwomps. During this time, though, the volcano erupts, with several Thwomps falling in and destroying the laboratory. One threatens to explode, and must be put out; Mario and Luigi do this by having Mario drink water and Luigi hammering him to spit it at the Thwomp, dousing it. Witnessing this event in the past causes inspires E. Gadd of the present to invent the Hydrogush 4000, a massive water pump. Mario and Luigi then have him pump water through the time hole leading to Thwomp Volcano to douse the mountain.
After discovering that baby tears are the Shroob's weakness, Mario, Luigi, and Princess Peach relate this to the professor. E. Gadd then uses the Hydrogush to pump a liquid similar in chemical structure to Baby Luigi's tears through the time holes, ridding the presence of the Shroobs and reversing the state of their victims.
After his lab is destroyed by the eruption of the volcano, young E. Gadd mentions his interests in studying ghosts, and that he would be buying a lab at the edge of Boo Woods, nodding toward his first appearance in Luigi's Mansion.
 Mario Party series
In Mario Party 5, Professor E. Gadd's garage is a minigame and was then featured as a game board in Mario Party 6. Also in Mario Party 6, when a player lands on a ? space E. Gadd will appear and let them try one of his inventions.
In Mario Party Advance, E. Gadd appear as the co-host of Play Land. The coins earned in the minigames to buy Professor E. Gadd's many "Gaddgets".
A magic wand bearing Gadd's logo later appears in Mario Party 7.
 Mario Kart series
E. Gadd's inventions are sometimes used as items in the Mario Kart series.
 Mario Kart DS
 Mario Kart Arcade GP series
E. Gadd makes a small cameo in Mario Kart Arcade GP as a statue in the background of the Diamond City course in the Wario Cup. His face, the logo of Gadd Science, appears on a building as well. This cameo carries over into the sequel, Mario Kart Arcade GP 2.
A device created by E. Gadd with the aid of the Mario Bros. which is designed to contain captured Boos. It is stored in the Bunker's Vault.
A handheld device that bears a striking resemblance to a Nintendo DS used briefly by E. Gadd to find Princess Peach in Mario & Luigi: Partners in Time. It has the ability to pinpoint which time period someone is trapped in. One of the Toads thinks he just made it up. Also, when Professor E. Gadd turns on his Hydrogush 4000, he uses a DS-like device.
An upgraded Game Boy Horror given to Luigi in Luigi's Mansion: Dark Moon. Not much is known about it, except that it can be used for communication.
Special parts that can be bought in the Super Duel Mode of Mario Party 5. They include the E. Gadd body, E. Gadd Jet, E. Gadd Engine and E. Gadd gun.
E. Gadd's garage is the garage he had in Mario Party 6. He also keeps his numerous inventions there. It also appears as a Rare Mini-Game.
Electronic portals in Luigi's Mansion: Dark Moon that can be used to transport people and things from one place to another. Comes in a pair, but only one of them has a panel on the top that must be turned on with a Strobulb flash for both to be activated.
The Flash Liquidizer Ultra Dousing Device, better known as F.L.U.D.D., is a water-spraying device used by Mario in Super Mario Sunshine. It is worn on Mario's back, and has various nozzle attachments which can be collected by breaking open boxes with E. Gadd's logo on the front. F.L.U.D.D. also has notable artificial intelligence and the ability to communicate with a voice. In certain ways, F.L.U.D.D. functions much as Navi did in The Legend of Zelda: Ocarina of Time.
The Game Boy Horror is a portable device from Luigi's Mansion that bears a striking resemblance to the Game Boy Color containing a built-in camera which E. Gadd can use to watch the action from the safety of his lab and contact Luigi. It also stores data including a map and anything Luigi has collected, and contains a special radar called the Boo Radar to find hidden spherical objects.
The Game Boy Horror SP is a upgraded version of the Game Boy Horror, given to Mario by E. Gadd in Mario & Luigi: Superstar Saga. It is another portable device, this time bearing a striking resemblance to a Game Boy Advance SP. It always gives the Bros. access to rare items in battle.
A machine that holds the ghosts captured in Evershade Valley and the ScareScraper in Luigi's Mansion: Dark Moon. It also provides research information on all captured ghosts including their spectral mass (weight).
A pale blue jacket that, when worn, turns characters into a ghost. When E. Gadd wore this in Mario & Luigi: Superstar Saga, Luigi got scared and used the Poltergust 3000 to vacuum him up.
The Ghost Portrificationizer is a large machine which works in conjunction with the Poltergust 3000. Certain ghosts captured can be entrapped in portraits to be hung in E. Gadd's gallery. The machine also works in reverse, which was utilized to free Mario from the painting he had been trapped in by King Boo. E. Gadd also commented that it took him twenty years to build.
A vault E. Gadd made to contain the ghosts of Evershade Valley and the ScareScraper in Luigi's Mansion: Dark Moon. It holds the Boo and Ghost Containers, a machine where Gemstones and their statues are stored, as well as a device which displays Poltergust 5000 upgrades, and a Bank Vault where treasure is stored and tallied.
A large water pump used in Mario & Luigi: Partners in Time. It's not portable like the F.L.U.D.D., but it does have a lot of power.
A magic wand in Mario Party 7, which has the E. Gadd logo on it. It is exclusive to Boo and Dry Bones. It was used to turn the characters invisible, making them impervious to traps, and to double their rolls on Dice Blocks for two turns.
The Magic Paintbrush is used by Bowser Jr. (as Shadow Mario) in Super Mario Sunshine. It is a large paint brush with the ability to paint various colors, though this magic paint can change the landscape, create portals, and create obstacles or enemies. It is unclear why the brush was made as well as why it was given to Bowser Jr., though some fans claim he stole it or E. Gadd was tricked by Bowser Jr. using his Mario costume. In Mario Power Tennis, Mario Hoops 3-on-3, Mario Super Sluggers, and Mario Sports Mix, Bowser Jr. uses his Magic Paintbrush to perform special moves.
E. Gadd uses the Pixelator to send Luigi, and his Toad assistants, from the various mansions in Luigi's Mansion: Dark Moon.
The Poltergust 3000 is a modified vacuum cleaner designed to entrap ghosts. It also has a "blow" function which allows it to expel elements it sucks up such as fire, water, and ice. Luigi uses this in Luigi's Mansion to defend himself from the many ghosts; it also makes a return in Mario Power Tennis where Luigi uses it as his defensive Power Shot, using its suction power to retrieve the ball. It also appeared as trophies in Super Smash Bros. Melee and Super Smash Bros. Brawl. The Poltergust 3000 is also used by Luigi in Mario Sports Mix for his special ability.
The Super Poltergust 3001 is an advanced version of a Poltergust 3000. It has the same functions as the Poltergust 3000, but is much larger thereby allowing it to be ridden on. When ridden, it hovers over the ground. It is capable of moving at high speeds. E. Gadd briefly uses it in Mario & Luigi: Superstar Saga.
The Poltergust 4000 is one of the vehicles used by Luigi in Mario Kart DS to race in. It is similar to the Super Poltergust 3001, though it does not float. The "barrel" of the car is the area Luigi sits on, and the nozzle rests on the ground. Emblems are placed on both sides of the barrel.
A vacuum that Professor E. Gadd creates for Luigi to vacuum up more ghosts in Luigi's Mansion: Dark Moon. Not much is known about the Poltergust 5000, except for the fact that it is a successor to the Poltergust 3000 and it creates a large circular sucking motion rather than the small sucking motion from the first game, making it a lot easier to defeat multiple ghosts at once.
This robotic entity of Mario races against players in the Rainbow Cup challenge game in Mario Kart Arcade GP 2. It spawns an infinite number of items and changes items depending on its place.
The café in the Beanbean Kingdom, founded and owned by E. Gadd. It does not have any toilets. At one point, E. Gadd puts up a larger-than-life-size portrait of himself. Every time Mario and Luigi mix a new drink, E. Gadd visits.
An intelligent suitcase used by the Mario Bros. on their quest in Mario & Luigi: Partners in Time. Its purpose is to manage the brothers' inventory and display their current status. It also helps the brothers by activating the Shroob Saucers that are used in the game, and eventually near the end develops the ability to return to the past before rescuing Princess Peach. It is known to use large and overly complex made-up words when he speaks, and upon ending its speeches, says "BACK TO ADVENTURE!"
Used by Princess Peach to visit the past at the beginning of Mario & Luigi: Partners in Time. It is powered by the Cobalt Star. It breaks at the beginning of the game but is repaired after the Shroobs are defeated.
A vacuum from Mario Party 7. It is a capsule item exclusive to Wario and Waluigi. It doesn't look much like the Poltergust 3000. Rather, it is yellow and purple (much like the two characters that use it), and features the E. Gadd logo. It is used to steal coins from other players.
 List of appearances by date
 Names in Other Languages