Sonic Runners had a collaboration event with Puyo Puyo!! Quest featuring multiple unique buddies and a special alt for Amy where she dresses as Amitie from the Puyo Puyo series. Isn't she cute?

Espio the Chameleon is currently voiced by Matthew Mercer, who is best known for playing characters such as Jotaro Kujo from Jojo's Bizarre Adventure and Fire Emblem's Chrom, among many others.

In IDW's Sonic the Hedgehog Winter Jam, Eggman is shown to be watching several incidental characters, including Barry, Gadget, Ian Jr., and most curiously, the Conductor and his wife. latter of which seems to be wearing little else but an apron.

In Five Nights at Freddy's: Secret of the Mimic, there is a cardboard cutout and costumes of a character named "Hedgehog Hudgie", an obvious parody of Sonic the Hedgehog. There are also green and pink variants, possibly referencing Manic and Sonia of Sonic Underground.

According to Archie's Sonic the Hedgehog Free Comic Book Day issue from 2012, during the brief time between the Genesis Wave and the Super Genesis Wave, Bunnie D'Coolette is stated to be Cream the Rabbit's cousin.

Surge the Tenrec's bike extreme gear in IDW's Sonic the Hedgehog is likely a modification of the Hang-On gear from Sonic Riders, which itself is a reference to Sega's Hang-On arcade game.

In the Chaotix's 30th Anniversary Special, Sonic and Amy momentarily escape from Vector and Espio, with the two only being depicted as outlines shaped to match their Sonic Adventure key artwork.

When selecting Mega Man in Sonic Racing: CrossWorlds, he poses similarly to key art from the first Mega Man game.

In Sonic Racing CrossWorlds, Proto Man strikes a pose based on his Mega Man 10 artwork when he performs a boost.

In the US Sonic CD manual, Amy Rose is erroneously referred to as "Princess Sally".

Despite appearing four years into the Sonic the Hedgehog series with Knuckles Chaotix, Vector the Crocodile is about as old as Sonic himself. The two were originally conceptualized together to be part of a rock band.

Mimic the Octopus was a so-called "assassin" with shape-shifting abilities. He can almost perfectly transform into anyone, with his main tell being the suckers on his hands. For some reason, when attempting to kill his former colleague Whisper, he greets her with an open hand.

They are both regarded as guardians btw

In contrast to his game counterpart, Fang (then Nack) wielded various types of realistic firearms in Archie's Sonic comics; they were drawn to fire "energy blasts" later on. At one point, he managed to fire a bullet into Mina Mongoose, back when these guns were real.

Did one for Shadow and Silver just in case Silver has very big hair

The 2007 game Sonic X for the Leapster uses modified Sonic the Hedgehog 3 sprites for Sonic, Tails, and Knuckles. More interestingly, the game depicts Amy Rose in the Sega Genesis sprite style 16 years before Sonic Origins Plus, albeit her modern design.

PLAYING AMY'S STORY IN SONIC ADVENTURE GET IN HERE GRAAAAAAAAAGH

Despite wearing high heels, Blaze the Cat is not only able to keep pace with Sonic, but even challenge him in speed. She's kind of scary.

Storm and the Babylon Guardian wear a similar necklace. This may suggest that it is a traditional Babylonian accessory.

While Shadow Androids are a unique robot copy separate from Eggman's usual builds, a Metal Shadow was once designed with the intent of appearing in Archie's Sonic the Hedgehog: The Complete Sonic Comic Encyclopedia. He was designed by comic artist Tracy Yardley.

we are talking about m&ms a lot for some reason

When Sonic assassinated King Arthur in Sonic & the Black Knight, it appears Sonic sliced him apart, as in his two following appearances in Sonic Runners and Sonic Rumble, King Arthur is nothing but a floating bust. He also brute forced his way into the real world to haunt Sonic.

The posing of Gerald Robotnik's render from Sonic X Shadow Generations is inspired by concept art of him from Sonic Adventure 2.