Professor E. Gadd

"I'm getting too old for this ghost-catching tomfoolery."

- Professor Elvin Gadd

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 ).

Background
Professor Elvin Gadd used to live on the foothills of the Thwomp Volcano, as depicted in the game Mario & Luigi: Partners in Time.

The Mario Bros. go back in time and end up saving E. Gadd's 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 seven years of absence, Professor Elvin Gadd is set to appear in the sequel, Luigi's Mansion: Dark Moon, where he has made an upgrade of his vacuum, the Poltergust 5000. Professor Gadd also introduces two new inventions: the Pixelporter, which is a machine that transports Luigi through pixels to different locations in the mansion, where cameras are placed; and the Dual Scream, which is a device that resembles a Nintendo DS and is capable of communication. 

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: 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 Cafe, 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 defeating 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
A flashlight known as the Gaddlight was used to scare away Boos when they tries to steal a Star or coins in Mario Party 4. A magic wand bearing Gadd's logo later appears in Mario Party 7, and players can use the coins earned in the minigames to buy Professor E. Gadd's many "Gaddgets" in Mario Party Advance.

Professor E. Gadd's garage was a minigame in Mario Party 5 and was then featured as a game board in Mario Party 6. In Mario Party 6, when a player lands on a ? space E. Gadd will appear and let them try one of his inventions.

Mario Kart series
E. Gadd's inventions are sometimes used as items in the Mario Kart series.

Mario Kart DS
The Poltergust 4000 kart used by Luigi is based off of his Poltergust 3000 invention. Also, he was going to be a playable character but was replaced by Dry Bones.

Mario Kart Arcade GP
E. Gadd makes a small cameo in Mario Kart Arcade GP in the background of the Diamond City course in the Wario Cup. His face, the logo of Gadd Science, appears on a building.

Inventions
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.
 * DS Time Radar

An upgraded Game Boy Horror given to Luigi in the sequel to Luigi's Mansion, Luigi's Mansion: Dark Moon. Not much is known about it, except that it can be used for communication.
 * Dual Scream

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 Battle Machine

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.
 * E. Gadd's Garage

The Flash Liquidizer Ultra Dousing Device, better known as F.L.U.D.D., is a water-spraying backpack used by Mario in Super Mario Sunshine. It 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.
 * F.L.U.D.D.

The Gaddgets appeared in Mario Party Advance. There were 80 total, and were very similar to the toys in the WarioWare games.
 * Gaddgets

A flashlight that is used to scare away Boos when they try to steal a Star or coins in Mario Party 4.
 * Gaddlight

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.
 * Game Boy Horror

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 striking resemblance to a Game Boy Advance SP). It increases the likelihood of earning rare items in battle.
 * Game Boy Horror SP

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.
 * Ghost Gown

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.
 * Ghost Portrificationizer

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.
 * Hydrogush 4000

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.
 * Magic Orb

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 and even create 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.
 * Magic Paintbrush

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.
 * Poltergust 3000

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.
 * Super Poltergust 3001

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.
 * Poltergust 4000

A vacuum that Professor E. Gadd creates for Luigi to vacuum up more ghosts in the sequel to Luigi's Mansion. 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.
 * Poltergust 5000

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.
 * Robo Mario

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.
 * Starbeans Café

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!"
 * Stuffwell

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.
 * Time Machine

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.
 * Vacuum Orb

Trivia

 * His name comes from the minced oath "egad," something that one says in amazement or shock.
 * In The Super Mario Bros. Super Show! episode "Robo Koopa", there is a scientist named Dr. Nerdnick who bears a passing resemblance to E. Gadd due to his similar appearance and the fact that he too speaks in incomprehensible gibberish.
 * Almost all of Professor Elvin Gadd's inventions are yellow, such as F.L.U.D.D, the Hydrogush 4000, the Gaddlight, and parts of the Coin Vacuum.
 * In Super Smash Bros. Brawl, one of the names that can appear whenever a player presses the random button when he or she is naming his or her custom stage is "EGADD".
 * Glasses with swirls are often seen in Japanese media, and are a feature Professor Elvin Gadd shares with Professor Frankly, Fawful, Francis, and Iggy Koopa.
 * Occasionally, Professor E. Gadd's voice-overs will include "Oyamaa", which is both his Japanese name and an exclamation of surprise. This happens even in overseas releases.
 * During the events of Luigi's Mansion, E. Gadd doesn't seem to remember either Mario or Luigi despite the fact he met them decades earlier on Thwomp Volcano. This is most likely because Luigi's Mansion was released before Mario & Luigi: Partners in Time.