The Maestro is a future version of the Hulk. I based this custom on the Future Imperfect story in which the Hulk traveled into the future and met an evil version of himself.

In this future world, all heroes had been killed after a nuclear war. Only the strongest one survived, the Hulk, who absorbed all the radiation, which drove him to madness. He became the tyrant who ruled over the humans of the post-apocalyptic Earth.

I used the Bowen statue of the Maestro as a reference. I made this with a DCU Arkillo base, DCU Brimstone fists, and head from a Marvel Legends Maestro.

***Update***
The custom Smart Hulk that the Maestro is facing off against was by raybot.