Sony is developing a Sinister Six team-up movie, one likely to include a wide variety of recognizable actors playing the titular villains. When the movie will finally arrive is currently anyone's guess, as Sony has wanted to get going on a Sinister Six film for about a decade at this point, since the days of The Amazing Spider-Man franchise. Back then, future Daredevil showrunner Drew Goddard was slated to write the script, and possibly direct as well.
Those plans were put on the backburner in 2015, when Sony brokered a now-famous deal with Marvel Studios that allowed Tom Holland's Spider-Man to become part of the MCU. That deal of course still continues today, with no indication that Peter Parker is leaving the MCU anytime soon. Despite that, Sony has plowed ahead with its growing Spider-Man-adjacent Marvel movie universe, which has so far counted Venom, Venom: Let There Be Carnage and Morbius among its ranks, with a Kraven the Hunter moving coming in early 2023.
For now, no director is attached to Sony's Sinister Six movie, although Goddard and Morbius helmer Daniel Espinosa at one point both appeared to possibly be in the running. A cast has yet to be confirmed either, but based on Sony's existing Spider-Man and Spider-Man extended universe movies, as well as casting reports and theories, educated guesses can be made as to what to expect. Considering Morbius' underperformance at the box office though, there's a chance Sinister Six might be in for yet another reworking before it arrives.
Spider-Man - Andrew Garfield
While there's always a chance that any Marvel movie going forward could incorporate the multiverse in some fashion, that's also not likely to be a creative well that is dipped into too often, lest it get overdone. With that in mind, it's been clearly established that the MCU is a different universe than where Venom resides, likely ruling out Tom Holland. Tobey Maguire also has history with his own version of Venom, which likely keeps him out of the running too. A logical move would be to sign up Andrew Garfield, who is not impossible to retcon into the Venom-verse due to his past movies not involving the character, and was widely seen as stealing every scene he was in during Spider-Man: No Way Home. Plus, he was in Sony's original Sinister Six plans back in the mid-2010s, making him the most natural fit.
Vulture - Michael Keaton
Morbius' credits scenes famously saw an appearance from Michael Keaton's Adrian Toomes, a.k.a Vulture, who was sent over from the MCU thanks to the multiversal havoc in Spider-Man: No Way Home. While the explanation for that is pretty thin, Toomes invites Morbius to form an alliance. The resulting team, should it happen, would undoubtedly be the Sinister Six.
Morbius - Jared Leto
As mentioned, the credits scenes of Morbius seem clearly designed to set up a Sinister Six movie team-up. Despite Morbius' critical and commercial failings, there has so far been no indication that Sony plans to release Jared Leto from his multi-film contract, or recast the character of Michael Morbius. Therefore, it seems safe to say a Sinister Six movie made anytime soon will include Leto.
Venom - Tom Hardy
This is another casting that is almost impossible to imagine changing, as the two Venom movies starring Tom Hardy as Eddie Brock have been big successes for Sony. The real question is not whether Hardy will play Venom, it is whether or not Venom will join the Sinister Six or oppose them. Despite being part of the group in past Marvel media, Hardy's Brock is decidedly positioned as a good guy for now. Therefore he seems more likely to team up with Spider-Man and fight the villain team than be part of it.
Mary Jane - Shailene Woodley
Who could play Mary Jane Watson in a Sinister Six movie is truly up in the air, as it has little chance of being Zendaya or Kirsten Dunst thanks to their respective involvements in the other established Spider-Man franchises. However, Emmy and Golden Globe-nominated actress Shailene Woodley was cast as MJ for Andrew Garfield's Amazing Spider-Man 2, only to see her scenes cut. If he ends up playing Spider-Man opposite the Sinister Six, it would be a perfect opportunity to bring her back into the fold.
Green Goblin - Dane DeHaan
Proceeding along the same lines, if the Green Goblin is part of Sony's Sinister Six, a good candidate for the job would be Dane DeHaan, who played the role in The Amazing Spider-Man 2. Notably though, his Goblin is the Harry Osborn version, not Norman as in the Sam Raimi Spider-Man movies. DeHaan was also in Sony's original plans for Sinister Six, making him another natural inclusion at this stage of production.
Rhino - Paul Giamatti
Paul Giamatti's Rhino may be a bit hard to take seriously after Garfield's Spider-Man ashamedly referred to him as a "Russian guy in a rhinoceros machine," but he would still be a good candidate for Sony's Sinister Six movie. He was again also in the studio's original plans for the team-up, and Giamatti is a generally terrific actor. If they reimagined his controversial Rhino, Giamatti could likely make it work.
Black Cat - Sydney Sweeney
While Black Cat's alter ego Felicia Hardy made a very brief appearance in The Amazing Spider-Man 2 (played by Felicity Jones), it is doubtful that will be followed up on. With current Hollywood it-girl Sydney Sweeney cast in Sony's upcoming Madame Web movie project, and rumors strongly suggesting she's playing Black Cat, it would make perfect sense for Sweeney to appear in Sinister Six. However, she would make much more sense as an ally for Spider-Man than an enemy, making her direct involvement with the team more unlikely.
Kraven the Hunter - Aaron Taylor-Johnson
This casting for a Sinister Six movie seems like a lock, as the Kraven the Hunter debut solo film is already in production, with MCU Quicksilver actor Aaron Taylor-Johnson set to play Kraven. Kraven is often a member of the Sinister Six in Marvel media, so it would not make sense to make a Sinister Six movie without him. However, it is worth considering the idea that if the Kraven movie fails as badly as Morbius did, Sony might decide to pump the brakes once again on making Sinister Six. There is no sense in building on top of a foundation that is not proven to be steady.