Sonic the Hedgehog protagonist Sonic the Hedgehog, a blue hedgehog able to run at supersonic speeds, and recurring villain Dr. Eggman, an evil scientist whose ambition is to conquer the world. Among Sonic's many allies, the most well-known include: Miles "Tails" Prower, a twin-tailed, highly intelligent yellow fox who is Sonic's sidekick and best friend; Amy Rose, a pink hedgehog who is Sonic's self-proclaimed girlfriend and a hero in her own right; Knuckles the Echidna, a coolheaded red echidna who is the guardian of the Master Emerald; Shadow the Hedgehog, an anti-heroic doppelgänger of Sonic with a dark past; and Metal Sonic, a
Sonic the Hedgehog as Wave Master, have composed the majority of the music in later games. Jun Senoue, a member of the band Crush 40 and sound director of the series, has written and performed the main theme tunes of both of the "Sonic Adventure" games, "Sonic Heroes", "Shadow the Hedgehog", and "Sonic and the Black Knight". Since the mid–2000s, the overall sound direction of the series has been handled by Tomoya Ohtani, who has served as the lead composer on "Sonic the Hedgehog", "Sonic Unleashed", "Sonic Colors", "Sonic Lost World", and "Sonic Forces". On several recent games, other non-Sega musicians have contributed