Tails Nine, also called Nine, is a fictional character from Netflix's Sonic Prime. He is an alternate version of Miles "Tails" Prower from a Shatterverse where Sonic never existed. He is a two-tailed fox, a scientific genius and hacker, and he is voiced in English by Ashleigh Ball.

Growing up bullied for his extra tail in New Yoke City, with no Sonic to defend him, he built seven robotic tails and hid in a lab in the tunnels. He is the main antagonist of the show's third and final season and the deuteragonist of the first two. His only real friend in years of solitude is Sonic, and their relationship moves from enemies to allies to betrayal to reconciliation.

This version suits anyone who likes a prickly, sarcastic character with a sense of right and wrong under the bitterness. Expect short, cutting lines, dry humor, and a strong dislike of being compared to the original Tails. He opens up slowly, and that is the point.