There is a lot of excitement going on in the world of Marvel and when it was announced on Oct. 1 that Jamie Foxx was in the final stages of negotiating the reprise of his role as Electro in the upcoming Spider-Man 3 movie, theories started to pop up on social media. And the big question was asked: Is the Sinister Six confirmed for the MCU?Jamie Foxx is reportedly coming back as Electro, now joining the Marvel Cinematic Universe.The Hollywood Reporter broke the news that Jamie Foxx is "in the final talks" to reprise the role of Electro in the upcoming Spider-Man installment starring Tom Holland as Spider-Man. He previously played the villain in The Amazing Spider-Man 2, which had Andrew Garfield in the lead role.The publication says the full details surrounding the movie are still being kept private, but most of the supporting cast of the previous movies are expected to be back for the next installment. This includes Marisa Tomei, Jacob Batalon, Tony Revolori, and Zendaya.It's also reported Jon Watts, the director of Spider-Man: Far from Home, is slated to direct this third installment from the Sony franchise. Kevin Feige and Amy Pascal are set to produce the movie which is dated to be released Nov. 5, 2021.When the news hit social media that it was looking increasingly more likely that Jamie Foxx would make an appearance in the upcoming Spider-Man, excitement started brewing. Not only because Spider-Man 3 sounds like it's going to be full of drama, fights, and everything that makes these movies great, but it might point to another big thing: The Sinister Six.So, what does Electro have to do with the Sinister Six?Anyone who is versed in the whole Spider-Man universe already knows the Sinister Six — a group of supervillains that appeared in the Spider-Man comic books published by Marvel Comics. The group comprises of enemies of Spider-Man, and we've seen several of them make an appearance in the cinematic universe already.The original version of the group was organized by Doctor Octopus, one of the more well-known villains in the storyline. He enlisted several other villains to join the group, including Mysterio, Vulture, Electro, Sandman, and Kraven the Hunter. \n\nSo far, we met Michael Keaton as Vulture in Spider-Man: Homecoming and Jake Gyllenhaal as Mysterio in the sequel Spider-Man: Far From Home.We previously met Alfred Molina as Doc Ock in the Tobey Maguire-led Spider-Man 2, and Kathryn Hahn voiced a female version of the character in Spider-Man: Into the Spider-Verse. The Sandman popped up in Tobey's Spider-Man 3, and he was played by Thomas Haden Church.However, like Electro's appearance in The Amazing Spider-Man 2, these appearances of Doc Ock and the Sandman don't count as their movies are not a part of the Marvel Cinematic Universe. That being said, if Jamie Foxx can crossover into the MCU, who's to say they can't too?So far, Kraven the Hunter has also not appeared in the MCU, but rumors arose earlier this year that Marvel was looking to cast him.Will the Sinister Six be making an appearance in the MCU?There hasn't been any official word from anyone at Marvel on if the Sinister Six is going to make its way into the Marvel Cinematic Universe. However, given how intricate the storyline is for the Avengers and having all those timelines add up, we're going to go out and guess (along with all the fans on social media) that yes, this is going to happen, and people are so excited for it.There's also a prediction out there that time travel may play a role, considering that Marvel just introduced time travel with Endgame. Perhaps time travel will be how Jamie Foxx's Electro jumps into the current timeline. Can Alfred Molina's Doc Ock do the same? Some fans are speculating even further that we may see Andrew Garfield and Tobey Maguire don the suit again, this time in the MCU."Sony wanted to do a Sinister Six movie, saw how good Spider-Verse did and how much people like big, time traveling crossovers and thought... what if we put them together?" one fan hypothesized. \n\nGuess we're going to need to be patient for a little while longer to find out if any more villains get added to the Spider-Man 3 lineup.