Warning: Contains SPOILERS for Sonic the Hedgehog 3!

Amy and Metal Sonic appearing in the third. Sonic the Hedgehog 4 will most likely continue this trend, meaning that the film will again have to tease what is coming next.

Sonic the Hedgehog 3's post-credits scene sees the titular blue blur accidentally run to a wooded area in New York, where he is surprised and attacked by a robotic version of himself. This is Metal Sonic from the Sonic the Hedgehog video games, but he isn't alone. Sonic soon finds himself facing off against an entire army of Metal Sonics, and they seem to be a bit overwhelming. Luckily, a cloaked, hammer-wielding character saves the day by smashing the robots, with her then revealing herself to be Amy Rose.

5 Eggman Nega

He Could Be Behind Metal Sonic's Sonic 4 Role

It has been highly theorized that Jim Carrey's Doctor Robotnik will return in Sonic the Hedgehog 4 in a different form, likely as Eggman Nega. Eggman Nega is a descendant of Ivo Robotnik from the future, with him coming back in time and acting as a more competent version of Ivo. These theories state that Eggman Nega could be behind the Metal Sonic army, sending them back in time to kill Sonic.

This Eggman Nega theory would require the Metal Sonics to be a secondary antagonist to Eggman, which may overshadow the popular metallic villain. Thus, another option would be to have Metal Sonic's creator remain a mystery throughout Sonic the Hedgehog 4, with the film only revealing the return of Jim Carrey as Eggman Nega in a post-credits scene.

4 Silver The Hedgehog

Building On Sonic 4's Potential Time Travel Story

The use of Metal Sonic and Amy Rose has led many fans to believe that Sonic the Hedgehog 4 will adapt Sonic CD, a story that will heavily involve time travel. However, Sonic CD isn't the only game that uses time travel, with it also being featured in 2006's Sonic the Hedgehog reboot. So, once Sonic the Hedgehog 4 gets Sonic CD's story out of the way, Sonic the Hedgehog 5 can build on the time travel story by introducing Silver the Hedgehog. Like in the game, Silver could travel back in time and try to kill Sonic, only to later realize his misunderstanding and Team Sonic.

3 Blaze The Cat

She Could Appear Alongside Silver

While the second and third Sonic the Hedgehog movies each only introduced one new character, Sonic the Hedgehog 3's post-credits scene introduced two, setting a massive precedent. So, if Silver the Hedgehog is featured in Sonic the Hedgehog 4's post-credits scene, then it is likely that Blaze the Cat will appear beside him. Although Blaze's origins have been changed a few times, when Silver is involved, Blaze is often presented as another time traveler from the post-apocalyptic future, meaning that it makes sense for her to appear as well.

2 Black Doom

Continuing Shadow The Hedgehog's Story

Sonic the Hedgehog 3 actually had two post-credits scenes, with the second one teasing the return of Shadow the Hedgehog. It isn't known if Shadow will return in Sonic the Hedgehog 4 or if he will get his own spinoff. If a spinoff movie does happen, it is more likely that Black Doom would appear as a villain in that. However, if Shadow becomes a recurring character in the main films, then Black Doom could be the villain of Sonic the Hedgehog 5, with him being set up in the post-credits scene of Sonic the Hedgehog 4.

1 Chaotix

They Would Be A Complete Change Of Pace

While there are plenty of villains in the Sonic the Hedgehog franchise, the movie series' post-credits scenes have mostly focused on Sonic's friends, with the villainous Shadow even becoming one after his debut. Thus, Sonic the Hedgehog 4 could pull off a similar trick by introducing Chatoix, a trio that could start out as an antagonistic force before becoming friends with Sonic.

Since Sonic the Hedgehog 3's post-credits scene kicked things up a notch by introducing two characters, Sonic the Hedgehog 4 could go even further by introducing three. Vector the Crocodile, Charmy Bee, and Espio the Chameleon are fun characters who alone may not generate much hype. By introducing them together, however, Sonic the Hedgehog 4's post-credits scene could introduce a unique story that finally isn't centered on the Robotniks, which would be a nice change of pace after Sonic the Hedgehog 3.