This article contains spoilers for the Sonic the Hedgehog film & game franchise. Ever since Paramount's animated take Sonic debuted on our screens Gerald RobotnikParamountJim Carrey has been offering up laughs as the often grotesque Ivo Robotnik since the first Sonic movie in 2020, but he returns in dual roles here playing the original villain and his nefarious grandfather Gerald. Not only is the performance the best thing about the film according to our reviewer, but it also introduces a key player in Sonic lore and one of the franchise's most evil but tragic villains. First appearing in the 2001 3D platformer Sonic Adventure 2, Gerald Robotnik is another super-intelligent scientist behind the mysterious "Project Shadow." Through the gameplay and numerous character flashbacks, players learn that the project was his scheme to find immortality. At first, it seemed like a selfish mission, until it was revealed that he was actually trying to save his granddaughter Maria who was terminally ill. We'll get to her in a moment, but otherwise his story is relatively similar to what we saw in Sonic 3. Though, while it appears Gerald died at the end of the film his video game history hints at a potential comeback for the villain in the already announced Sonic 4. After he disappears in the games, Gerald was forced to work for G.U.N to continue his experiments, and also ended up in Prison Island which we saw briefly in this film before being executed. Seems unlikely that the PG film franchise will adapt that bleak part of his lore but, seeing as they did bring to life the deeply controversial murder of a child this time round, never say never. MariaParamountSpeaking of the famously celebrated Sonic franchise child murder, we finally meet Maria (Alyla Browne), Shadow the Hedgehog's (Keanu Reeves) best friend, cousin of Ivo Robotnik, and the tragically sick granddaughter of Gerald who inspired his genocidal rage in the movie and games. Via an extensive sequence of flashbacks, we witness the happiness Maria brought to Shadow's life and the sadness that her untimely demise at the hands of G.U.N caused Shadow and Gerald which, essentially the same lore as in the games. There though, she was actually shot by a G.U.N agent marking a dark moment for the franchise as a whole as she attempted to help Shadow escape the military group's clutches. While Maria won't be getting resurrected in the next movie her impact will still be felt. Shadow is still alive at the end of the movie meaning that her loss will likely still be driving him especially as he takes on a more heroic role in the next film. So don't count out more Maria flashbacks even as the franchise moves on from her untimely death. ShadowParamountThe Ultimate Life Form has long been seen as one of the coolest characters in Sonic canon so, when Keanu Reeves one of the coolest actors on Earth was cast to play him, it felt like a match made in heaven. The inclusion of Shadow immediately meant that the film would hit on some of the darker lore we've already mentioned, as well as setting up a recurring rival or ally for Sonic. We get an interesting reimagining of his origin here, where he's an organic lifeform like Sonic, Knuckles, and Tails rather than a creation of Gerald Robotnik's like in the game. In that original lore, Shadow was created as part of the elder Robotnik's plan to save his granddaughter Maria's life and struggled with a heavy existential crisis when he couldn't help cure the young girl. As we mentioned above, Maria comes to a fateful end in both the games and the films, shaping his future as both an antagonist and ally to Team Sonic. Another vital Sonic Adventures 2 addition, Shadow is an incredibly powerful character who was inspired by famed anti-heroes like Todd McFarlane's Spawn. Just like the end of Sonic 3, Sonic Adventures 2 ended with Shadow's apparent death but, since that game, he's reappeared multiple times, becoming one of the franchise's most popular characters. When it comes to what we can expect for Shadow in Sonic 4, we wouldn't be surprised to see the aliens known as the Black Doom, who are part of his classic origin. We could also see the evil Phantom Copy of the anti-hero come into play as a potential antagonist for him and Sonic to team-up against once again. Super ShadowSegaJust as Sonic 2 finally bought the golden-hued super-powered heroic evolution of Sonic Super Sonic Sonic 3 introduces the souped up version of Shadow too. The action happens in the third act as the pair use the Chaos Emeralds to go Super in order to save the day and defeat Robotnik Sr. In the original game, this is more aesthetic than actual power-based but, in the movie, we saw the Super transformations of the characters gave them extra speed, power, and immense hit impact. Its another nice nod to his game origins as well as an epic final act battle, and we'll surely see Super Shadow and Sonic when Sonic 4 hits in 2027. Metal Sonic SegaThe first of the film's post-credits scenes reveals that one of Sonic's most dangerous foes has arrived in the Paramount Sonic universe. Metal Sonic a futuristic evolution of Eggman's badnik bots has been haunting gamers and the titular hero since Sonic the Hedgehog CD in 1993. The super-powered, high tech menace is like a Bizarro version of the heroic hedgehog, instead of kind and fun loving hes cold and brutal. And even more terrifying here is that in the post-credit scene we actually get multiple Metal Sonics, ready to take down the blue blur. Metal Sonic is regarded as one of Sonic's most fearsome and ferocious enemies, imbued with sentience thanks to his AI chip. Metal Sonic is often allied with Eggman. But will that be true in Sonic 4 even though it seems that Jim Carrey's vivacious villain has seemingly been vanquished? We would love to know the answer! However, what we can say for certain is that the metal menaces have a serious problem on their cold-shiny hands...Amy RoseSegaA mysterious ally arrives just in time to aid Sonic against the barrage of Metal Sonics in the mid-credits scene. Swinging around a giant weapon with sleek efficiency, the hooded helper reveals herself to be none other than one of Sonic's oldest friends and biggest fans, Amy Rose! That weapon is, of course, her Piko Piko Hammer, probably the most legendary of all weapons in Sonic cannon canon (pun intended). Amy Rose also first appeared in Sonic the Hedgehog CD, and she's since become a staple of nearly all Sonic games as well as the female lead of the franchise (sorry Rouge fans, maybe one day soon she'll get some proper respect from Paramount). Amy's not just a fighter she has a mystical side as well thanks to her love of fortunes and tarot and hopefully Sonic 4 will show us all the facets of this fascinating and funny heroine.Rosie Knight is a contributing freelancer for IGN covering everything from anime to comic books to kaiju to kids movies to horror flicks. She has over half a decade of experience in entertainment journalism with bylines at Nerdist, Den of Geek, Polygon, and more.