Neo Metal Sonic in the Last Story cutscene.
Neo Metal Sonic is a transformation of Metal Sonic, featuring as the robot's primary form in Sonic Heroes. With elongated spines somewhat like Rocket Metal's, Neo Metal Sonic also sports spiky shoulder epaulettes and a billowing, feet-length cape.
Neo Metal is the "mystery monster" of Sonic Heroes, and the game's true antagonist. Metal Sonic takes this form when he reneges against his master, Doctor Robotnik, and (via Froggy) acquires Chaos' ability to shapeshift. The robot imprisons his creator and takes over the Eggman Fleet by impersonating Eggman, intending to conquer the world and create a robotic empire. To this end he lures in the various Teams of heroes, copying their combat data while disguised as the Doctor.
In the Last Story, Neo Metal Sonic reveals himself atop the spire of the Final Fortress, but only seconds later transforms into the dragon-like Metal Madness and Metal Overlord. At the very end of the game he transforms back down to the classical Metal Sonic model, losing his lengthy spines and cape.
The name "Neo Metal Sonic" is never used in-game during the English version of Heroes, but it is confirmed in Sonic Rivals, where 'Neo Metal Sonic' is the 150th (and final) collectible card.
| Characters in the Sonic the Hedgehog game series
||Sonic (Super, Hyper, Darkspine, the Werehog, Excalibur) | Tails (Super) | Knuckles (Super, Hyper) | Amy Rose | Cream | Big | Blaze (Burning) | Emerl | Silver (Super) | Marine | Lumina Flowlight | Chip | Shahra | Knights of the Round Table | Caliburn | Yacker | Sticks | Avatar
||Shadow (Super) | Rouge | Espio | Charmy | Vector | Mighty | Ray | Chaos (Perfect) | E-102 Gamma | E-123 Omega | Bean | Bark | Jet | Wave | Storm | Shade | Merlina
||Dr. Eggman | Metal Sonic (Kai, Rocket, Neo, 3.0) | Mecha Sonic (Super) | Fang | Witchcart | Battle Kukku Army (15th, Speedy, Dr. Fukurokov) | Tails Doll | Metal Knuckles | E-Series | ZERO | Void | Biolizard | Gemerl | Eggman Nega | Black Doom | Angelus | Iblis | Mephiles | Solaris | Erazor Djinn | Captain Whisker | Johnny | Master Core: ABIS | Ix (Super) | Dark Gaia | King Arthur | Orbot | Cubot | Deadly Six (Zavok, Zazz, Zomom, Master Zik, Zeena, Zor) | Hard-Boiled Heavies | Infinite
|| Sonic/Heroes | Rose | Dark | Chaotix | Babylon
|| Gerald & Maria Robotnik | Froggy | Chao | Omochao | Cheese | Chocola | Vanilla | Tikal | Pachacamac | E-101 Beta | Illumina | President | G.U.N. Commander | Elise | Duke of Soleanna | Coconut Crew | Vikings | Professor Pickle | Wentos | Don Fachio | Heavy and Bomb | Tiara Boobowski | Honey | Flicky | Animals | Wisps