This is Syn Shenron, one of the seven Shadow Dragons that were born as a result of overusing the Dragon Balls. Syn is the final villain in the series and is the ultimate evil in the universe.
Syn is a big guy(he is definitely one of the biggest characters in both Dragon Ball Z an GT) who is at least the size of Bojack and looks just like Dabura. He has several spiky horns on his back and elbows which can inflict fatal damage to anyone who accidentally lands on them. The one-star ball is clearly visible on his forehead and is colored blue to indicate that it’s filled with negative-energy.
Syn’s only goal is to ensure the destruction of the universe. Anything or anyone that is not with him is against him, as shown when he killed his fellow Shadow Dragon, Nuova Shenron, for trying to help Goku regain his vision. He will annihilate anyone that dares stand on his way. With Syn’s frightening might threatening to destroy everything in existence, this could be one matter that Goku may not overcome.
Syn Shenron is the strongest of all the Shadow Dragons and is also the strongest villain in the series. He’s not just the strongest of the villains, he’s also stronger than any of the Z-Fighters. He eliminates Nuova Shenron, who’s power is already equal to Super Saiyan 4 Goku’s, with one uncharged-blast. He destroyed the city where he and Goku were standing by just powering up.
Syn’s power level is slightly greater than either Super Saiyan 4 Goku or Vegeta’s. Although Syn is incredibly powerful in his current state, his body is designed to transform into a much more powerful being upon gobbling up the Dragon Balls. He was able to withstand Super Saiyan 4 Goku’s fully-charged X10 Kamehameha without a single scratch on his body and he easily defeated him. He temporarily put the offending Gohan to sleep with a rather weak punch to the stomach, and he was able to easily blast the mighty Majuub, who was holding him off in order to buy Goku the time to get the energy that he needed, out of the way. However, it wasn’t until Goku succeeded in getting the energy of his reinforcements that Syn Shenron found himself at a disadvantage.
After surviving a powerful Kamehameha Wave from Goku, Syn revealed to everyone that he was yet to achieve his true power by swallowing the Dragon Balls, which transformed him into Omega Shenron, his ultimate form.