Many characters in the Sonic the Hedgehog franchise find themselves allied with the titular blue blur. However, some characters aren't just rivals of Sonic but are morally questionable villains in their own right. The greatest example of this throughout the Sonic games is Shadow the Hedgehog.
Shadow first appeared in Sonic Adventure 2 and has since become a mainstay of the franchise's main series. He appears as a playable character in Sonic Heroes, Sonic the Hedgehog (2006), and even his own self-titled game. These moments throughout the series are some of his most heinous actions against Sonic.
8 Shadow Is Deemed A Threat To Humanity
Unlike his blue counterpart, Shadow was created in a lab by Professor Gerald Robotnik. Through genetic engineering, Shadow was created as part of an experiment to cure Gerald's granddaughter, Maria, from a deadly illness. As a result, he's often considered the "Ultimate Lifeform" due to his immortality.
Unfortunately, Shadow's great power wasn't deemed safe by the U.S. government. He was subsequently deemed a threat to humanity and ordered to be frozen in suspended animation. This would be a common occurrence for Shadow, who is often taken out of commission in-between games by some unknown evil organization.
7 Shadow Fails To Escape The Government
Shadow did not surrender to the government easily. After forming a strong bond with Maria, the two plotted an escape from Gerald Robotnik's lab. However, a military organization called the Guardian Units of Nations (G.U.N.) thwarted them, killing Maria in front of Shadow and taking him into custody.
As a result of Maria's death, Shadow has been traumatized. Even later in the Sonic series when he loses his memory, he still retains his love for Maria. This serves as his primary motivation in the games, wanting to make the world better after promising her, while also grappling with his disdain for humanity.
6 Shadow Teams Up With Dr. Eggman
Shadow makes his first appearance in-game in Sonic Adventure 2 as a boss character for Sonic. In his own storyline, however, Shadow is freed from suspended animation by Dr. Eggman, who initially mistakes him for Sonic. As thanks for saving him, Shadow tells Eggman to gather the seven Chaos Emeralds for him.
Shadow later joins Eggman in the mad scientist's quest to conquer the world. However, Sonic stands in their way, causing the two look-alikes to battle at several points in the game. Along the way, however, Shadow slowly begins to remember his past, particularly his relationship with Maria.
5 Shadow Secretly Plans His Revenge
By the end of Sonic Adventure 2, Shadow has done a lot of evil stuff. The worst of it is framing Sonic for his misdeeds and creating public doubt around Sonic's heroic nature. However, through the restoration of his memory, Shadow is finally able to see Dr. Eggman for who he is, and betrays him, allying with Sonic.
Together, Shadow and Sonic thwart Eggman's plans to destroy the world. This is one of the few moments in the series where the two are on the same side. Finally, unable to handle the power of the Chaos Emeralds like Sonic, Shadow plummets to the Earth after the final boss battle, where he is believed to have died.
4 Team Dark Vs. Team Sonic
Thanks to popular demand, Shadow makes a return appearance in Sonic Heroes. He is discovered by Rouge the Bat in one of Dr. Eggman's bases, surprising the burglar. After Shadow saves Rouge from an attack by E-123 Omega, the three learn that they have a common enemy in Dr. Eggman and team up.
With their eyes set on revenge, Team Dark won't let anything get in their way. That especially includes Team Sonic, made up of Sonic, Tails, and Knuckles. At one point in the game, the two teams battle to see who can make it to Dr. Eggman first. Though both teams have a common goal, they remain rivals at this point.
3 Shadow's Allegiances Are Ambivalent
There are many moments in the Sonic games where Shadow comes to Sonic's aid. However, players are given a choice to control Shadow's morality in Shadow the Hedgehog, the character's solo game. The game's narrative finds an amnesiac Shadow having to choose between helping G.U.N, Sonic, Eggman, or another foe...
This fourth choice for Shadow is Black Doom, an alien who leads an army called the Black Arms. Shadow discovers in this game that Black Doom's blood was actually used by Gerald Robotnik to create him. Based on the players' choices, Shadow's decision-making can prove to be less than what Maria had in mind for him.
2 Shadow Creates Mephiles The Dark
Shadow is one of three lead characters in Sonic the Hedgehog, often referred to as Sonic '06. When the game begins, Shadow has become an agent of G.U.N, rescuing Rouge the Bat from a mission to Eggman's base. However, the plan goes wrong, and Shadow destroys the "Scepter of Darkness."
The Scepter of Darkness' destruction causes a seal to be broken, freeing a being known as Mephiles the Dark. Mephiles takes on the form of Shadow the Hedgehog and sends Shadow and Rouge to the distant future after he's destroyed it. Eventually, Mephiles even kills Sonic before the hero is revived and defeats him.
1 Shadow Attempts To Rescue Eggman
Shadow makes another appearance in the little-known PSP game Sonic Rivals. This racing game has a typical Sonic game story, though here, Shadow is once again at the service of Dr. Eggman. Shadow responds to a call from Eggman at the start of his episode, following a transmission to rescue the doctor from an evil force.
Eventually, Shadow comes face-to-face with Silver the Hedgehog, who initially debuted in Sonic '06. Shadow nonetheless continues to fight those who try to hunt down Eggman, and it takes him a while to realize that something's off about the doctor. Little does Shadow know that the Eggman in this game is actually... a card?