Heavy King

The Heavy King is the secondary antagonist of Sonic Mania. It is the leader of the Hard Boiled Heavies; an elite group of robots who were all empowered by the Phantom Ruby and serve Dr. Eggman.

Heavy King
Like the other Heavies, the Heavy King was once an ordinary Eggrobo. However, after being exposed to the Phantom Ruby’s power, its appearance and personality changed.

Matching the Heavy King's name, it has a quite stereotypical knight/king design. It has a curved protuberance on its head, golden-bronze armor, a white crown symbol on its upper red and black colored body, spiked knee joints, spikey metallic shoulder pads, a red cape, and red-golden feet.

Phantom King
In this form, the Heavy King retains most of its older features, like the red and golden color scheme. However, its white crown is now a very intense red color and its armor is even more gold. It also has notably bigger arms and loses its legs, but instead gains the ability to fly. Although its most notable feature is its huge size.

Biography
The Heavy King was made by Eggman himself as a powerful robot along with the other Hard-Boiled Heavies in order to do things for him that he would never be able to do, however, one day, Eggman told The Heavy King and the other heavy-boiled heavies should go get the Phantom Ruby, it was a new powerful force, that Eggman had to get his hands on, so he sent the Hard-Boiled Heavies, but the Heavies got corrupted by the Ruby instantly, it made them insane and gave them their own personalities.

After collecting the Phantom Ruby, the Phantom Ruby transported Sonic, Knuckles, and The Heavies to the Green Hill Zone, Sonic didn't fully manage to steal the ruby from them, The Heavies ran away.

When Heavy King along with the other heavies came back to Eggman, Eggman tried to catch orders at them, but they didn't listen and was stubborn as always, Eggman eventually just snatched the Ruby from them and they ran away.

While the Heavy Rider was distracting Sonic, King took advantage and took the chance of snatching the Master Emerald, while it did manage to get the Master Ruby to make itself more powerful, it STILL didn't manage to defeat Knuckles, and failed at collecting it.

The last time the Heavy King was seen in the game, was at the very end of it, when it plays a role as the true final boss, it had finally succeeded in making itself the powerful force it always wanted to be, and it became the Phantom King, it was now more powerful than it had ever been before, but this also made it insane at it's highest level, and started attacking Dr. Eggman himself, Sonic transformed into Super Sonic and battled both Eggman and the Phantom King, emerging victorious.

Personality
The Heavy King, unlike the other members of the Hard-Boiled Heavies, is played more seriously. It is strongly hinted that he rules the Heavies with an iron fist. He is also certifiably insane like the rest, though this is the fault of the Phantom Ruby as he was once a normal egg-robo before excavating it.

Trivia

 * In the opening of Sonic Mania, when the Heavy King appears as a silhouette, The Heavy King doesn't have red eyes, which he has in the rest of the game, but actually yellow eyes.