What kind of animal is Tails in "Sonic the Hedgehog"?

The answer is: Fox

Miles "Tails" Prower is a fox, and that name itself is a gloriously terrible pun on "miles per hour." SEGA's designers wanted someone who could match Sonic's speed but bring something new to the gameplay. They landed on a fox with not one but two tails because... why not make it weird?

The original concept sketches included a tanuki (Japanese raccoon dog), a squirrel, and even a human kid. But the twin-tailed fox won out because it let players literally fly through levels by spinning those tails like rotor blades. The developers loved how ridiculous it looked watching a little fox helicopter himself around using his own tails.

The character started as "Miles," but playtesters kept calling him "Tails" because, well, look at him. SEGA embraced it and made it his nickname. They also gave him a fear of lightning and made him a mechanical genius who could build his own airplanes at age 8. Because if you're going to have a flying fox who can spin his tails like helicopter blades, you might as well make him a child prodigy too.

Players fell in love with the little fox so completely that he got his own game, "Tails' Skypatrol," where he flies around solving puzzles without Sonic anywhere in sight. Not bad for a sidekick who started life as a way to help players reach high platforms.