Shadow Mario (also known as ? in the Super Mario Sunshine instruction manual) is a doppelgänger of Mario and serves as the main antagonist of Super Mario Sunshine. He has the same appearance as Mario, except that his body is blue and has the consistency of liquid, and he has glowing red eyes when angry. He also has a long, red tongue, which he occasionally sticks out at Mario to taunt him. Shadow Mario wields the Magic Paintbrush, an invention designed by Professor Elvin Gadd. With the brush, Shadow Mario can magically create large quantities of Graffiti, which occasionally spawns lesser enemies. He used this power to vandalize all of Isle Delfino with varying amounts of Graffiti, thereby making Mario the main suspect in the trial held thereafter. Later in the game, it is revealed that Shadow Mario is actually Bowser Jr. (Bowser's son) masquerading as a Mario look-alike. He does so by using a blue bandanna which he wears around his neck that has Mario's nose and mustache drawn on it. When he wears this over his mouth, similar to a mask, it allows him to assume Mario's form. It is unknown how Shadow Mario originally acquired the Magic Paintbrush, though it is suggested that Professor E. Gadd gave it to him, perhaps having mistaken Shadow Mario for the actual Mario, or that Bowser Jr. simply stole it from him.
 Super Mario Sunshine
At the beginning of Super Mario Sunshine, Mario, Princess Peach and Toadsworth are seen traveling to the island resort of Isle Delfino via Peach's private airplane to get some much-needed rest and relaxation. The first time Shadow Mario is seen is in the background of the welcome video that plays on a television in Peach's airplane as they approach the island. He is seen as nothing more than a black silhouette holding the Magic Paintbrush and jumping around the landscape behind several Piantas, who appear to be unaware of his presence. Peach is the only one on the plane who seems to notice him, though, as Mario and Toadsworth appear to be more preoccupied with the seafood and the relaxing atmosphere. Though she tries to inform them of what she has seen, she eventually gives up and the plane flies on. Eventually, they come to a screeching halt on the runway of the Delfino Airstrip.
When they exit the plane, they discover that the plane narrowly missed running directly into a large quantity of Goop, inside of which resides a Polluted Piranha Plant. At this point, Peach looks up and sees Shadow Mario for the second time, though this time he is simply standing on top of a small water tank watching the new arrivals. When she tries again to alert Mario and Toadsworth of his presence, they look up, only to find that he has disappeared. Toadsworth attributes this to the heat, saying that it is beginning to affect Peach's reasoning and immediately requests that Mario travel to the mainland and find some assistance. After Mario has retrieved F.L.U.D.D., defeated the Polluted Piranha Plant, and collected the first Shine Sprite, two Isle Delfino policemen arrive and escort Mario to a courthouse, where he is put on trial for the crime that Shadow Mario has committed: covering the entire island in toxic Graffiti. During the trial, Mario is found guilty of vandalizing the island, despite the fact that the true criminal was Shadow Mario. Worse yet, Mario is then thrown in jail by the Isle Delfino Police and subsequently ordered to clean the entire island of his "vile handiwork." Until he does so, he is forbidden to leave the island.
Shortly after the trial, Shadow Mario appears again, this time standing atop the Grand Pianta Statue in Bianco Square. In his first major act of the game, he jumps from on top of the statue and grabs Princess Peach, throwing her over his shoulder and running away with her. Mario immediately chases after him, spraying him with water from F.L.U.D.D. Eventually, he drops the princess and escapes, appearing back at the foot of the Grand Pianta Statue. When Mario tracks him down, he paints a multicolored "M" on the bottom of the statue and disappears inside. Following him by jumping inside the Color Portal, Mario finds himself at the beginning of the first level in Bianco Hills, The Road to the Big Windmill. Shadow Mario is seen standing next to another Polluted Piranha Plant spitting out Piranhabons in the level overview, but he will be gone by the time Mario finally makes it to that point in the level.
Shadow Mario's next appearance comes much later in the game, where he is seen on the west side of Delfino Plaza in a Bowser-shaped boat, having kidnapped Peach once again. When Mario attempts to confront him, he sticks out his tongue at him, climbs inside the boat and escapes to Pinna Island with Peach. Mario follows him by jumping into a nearby cannon which leads to the amusement park. Once there, Mario enters the park and chases Shadow Mario to a small circular pool near the Roller Coaster. Shadow Mario jumps and hovers over the middle of the pool, as the ground begins to shake. The pool splits (referencing a noteworthy religious moment) to reveal a large Mecha-Bowser robot emerging. Shadow Mario's eyes glow red as the gigantic robot breathes fire. The director of Pinna Park, believing that this is all an elaborate promotional stunt, allows Mario to use the Roller Coaster to fight back against Shadow Mario's enormous robot. Shadow Mario (now in the cockpit of Mecha-Bowser) attacks Mario by launching multiple Bullet Bills at his small Roller Coaster car as it rides along the track. Mario must avoid these while simultaneously attempting to launch water rockets at the robot to disable it. Eventually, the robot becomes too damaged to continue its attack and becomes immobile as Mario exits the Roller Coaster.
Shadow Mario then opens the cockpit of the robot and reveals his true identity: Bowser Jr. He goes on to explain that he had been told by his father, Bowser, that Princess Peach was his mother and that she had been kidnapped by the "evil" Mario, who, according to Bowser, never fights fair. Thus, Bowser Jr. disguised himself as a Mario look-alike and polluted the entire island with Graffiti, a crime for which he framed Mario in the hopes that he would be sent to prison. To his dismay, they did not lock him up. He also reveals that he has been using a Magic Paintbrush to commit the crimes, which "makes all his wishes come true" when he draws with it. He claims that a strange old man in a white coat gave it to him. That said, Bowser Jr. tells Mario to stop following him and then activates a large hot air balloon incorporated into his robot cockpit. Mario watches as Bowser Jr. pilots the balloon to Corona Mountain, taking Princess Peach with him.
When Mario has successfully defeated Shadow Mario in Episode 7 in each of the seven worlds (see below for more information), the final major event of the game is triggered: the flood. When Mario returns from the previous world, Delfino Plaza is flooded with water previously held inside Corona Mountain. A short cutscene shows Shadow Mario leaping off the top of the Shine Gate and making his way to the small opening leading into Corona Mountain, where he waits for Mario. When Mario approaches him, he quickly runs into the opening and disappears. When Mario enters the opening, Shadow Mario is gone and the real Mario must now make his way to the top of Corona Mountain, where the final boss battle awaits. When Mario finally reaches the top, he finds Bowser, Bowser Jr. and Princess Peach in a large, slime-filled hot tub. Bowser, enraged that Mario has ruined his family vacation, begins to attack Mario by breathing fire at him, while Bowser Jr. fires multiple Bullet Bills at Mario. After Mario has Ground Pounded five separate areas of the hot tub, it is turned completely upside down, releasing the final Shine Sprite and initiating the ending sequence.
At the end of the game, Bowser Jr. and his father are seen floating on a small raft on the outskirts of Isle Delfino, at which point Bowser finally attempts to tell him that Princess Peach is not his mother, though it is revealed that Bowser Jr. already knew. After telling his father that he wants to fight Mario again when he is bigger, Bowser agrees, but says that they should rest awhile. After the credits (if Mario did not collect 120 Shine Sprites), it is revealed that Bowser Jr. lost his Magic Paintbrush, as Il Piantissimo is seen discovering the brush on the sands of Gelato Beach, where it had somehow landed after the battle. It is unknown what Il Piantissimo does with the paintbrush or whether or not he even picks it up.
 Other Appearances
Aside from his periodic appearances throughout the game's main storyline, Shadow Mario also appears once in every world in the game to cause additional trouble for Mario. He appears only in Episode 7 of each world (with a few minor exceptions), where Mario must chase him through a certain part of the world, spraying him with F.L.U.D.D. until he drops to the ground. Each time Mario successfully catches Shadow Mario, he is forced to relinquish one Shine Sprite, after which he quickly disappears. In addition to this, he also appears at least once in each world (aside from the situations listed above) when Mario enters a secret level or area. In these situations, Shadow Mario arrives before Mario enters the secret area and takes F.L.U.D.D. from him, leaving Mario to complete the level without F.L.U.D.D.'s assistance. He also appears in a few other levels in the game, which are usually directly related to the storyline of the game in some way.
The levels in which he appears are as follows:
Levels in bold are levels specific to Shadow Mario for that particular world.
Shadow Mario also makes a few other minor appearances in Delfino Plaza, where he holds a specific item which Mario needs to progress in the game. He first appears holding a Yoshi Egg, then a Turbo Nozzle, and finally a Rocket Nozzle. Mario must chase Shadow Mario through the plaza and spray him as he normally would to defeat him, after which Mario is free to claim the item. When Shadow Mario falls to the ground, he complains that he was just about to use whatever he was holding before Mario interfered, and then disappears. The next time Mario returns to Delfino Plaza, the item he recovered is now placed in its permanent position as opposed to the location where Shadow Mario dropped it.
 Mario Golf: Toadstool Tour
Shadow Mario makes an appearance as an unlockable character in Mario Golf: Toadstool Tour. However, Bowser Jr. is also a playable character in the same game. Therefore, it is unknown if this Shadow Mario is an alternate version of Bowser Jr. or if it is someone else in disguise (but this could be disregarded as Metal Mario is playable in Mario Golf). This could be Il Piantissimo, as he found Shadow Mario's Magic Paintbrush in Gelato Beach at the end of Super Mario Sunshine. In the game, Shadow Mario is a light character. His maximum hit is 275 yards, and causes the ball to curve to the left when hit. In order to unlock Shadow Mario, the player must complete all of the Ring Attack holes with any one character.
 Super Smash Bros. Brawl
Shadow Mario appears as a collectible sticker in Super Smash Bros. Brawl. He also appears on a wanted poster in the Isle Delfino level.
 Game Appearances
 Names in Other Languages