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 swiped a floating ring out of Gollum's grasp inside a dark cave. (NOTVALID: New Adventures Await!)

Sonic had apparently heard of the Doctor before meeting him, and was impressed when he erroneously heard that he named the sonic screwdriver after him. (NOTVALID: LEGO Dimensions)