Sonic the Hedgehog (character)

Sonic the Hedgehog was the main character in the video game of the same name.

He was a blue hedgehog. (PROSE: Business Unusual)

Ace joked with Dr John Watson that whatever the Rakshassi were worshipping, it wasn't Sonic the Hedgehog. (PROSE: All-Consuming Fire)

Martha Jones once described the Tenth Doctor's hair as "very Sonic the Hedgehog", although the Doctor said he was going for more of a Sid Vicious vibe. (PROSE: Forever Autumn)

Non-valid appearances
Sonic appeared as a playable character in LEGO Dimensions.

In his debut trailer, he appeared inside either the First or Second Doctor's TARDIS and ran up beside the Twelfth Doctor, who was looking at his blackboard. Upon noticing Sonic, the Doctor whipped out his sonic screwdriver in surprise.

When paired together in-game, Sonic will reveal to having already heard of the Doctor, as well as, erroneously, the fact that he named a screwdriver after him.