Neo Metal Sonic is one of Metal Sonic's forms seen in Sonic Heroes. He takes this form throughout most of the game in which he uses to disguise himself as Dr. Eggman and to copy the data of whom he fought against in order to make himself more powerful.
The first time he reveals himself to the heroes is in the last story of Sonic Heroes. Having gained all the data he needed, Neo Metal Sonic began destroying the Final Fortress' tower with a large bolt of lightning and then uses the debris to transform into a stronger form, Metal Madness and later Metal Overlord. He is later defeated by Team Super Sonic and as a result, the weather changes into a clear blue sky as he reverts back to his original form and deactivates.
Neo Metal Sonic later appears in his Eggman disguise piloting the Egg Emperor in Sonic Generations.