Dabura

Dabura (ダーブラ, Dābura) is a ruler of the Demon Realm. Existing for thousands of years, Dabura is placed under the wizard Babidi's control by a spell, becomes his right-hand man, and thus does his bidding. His name is originally taken from the last half of the famous incantation, "Abracadabra".

His title, "Demon King", is not to be confused with that of one of the previous villains, Demon King Piccolo from Dragon Ball.
Under Babidi's control, Dabura inspected the Earth in Age 474. He was scanning for any humans with impressive power levels, however, he found none (as none of the Z Fighters were born at the time).
Dabura is first seen when Goku, Gohan, Vegeta, Piccolo and Krillin are led to Babidi's spaceship by Kibito and Supreme Kai to aid them in preventing Majin Buu's awakening. Babidi and Dabura are aware of their hiding place in the mountains nearby and, as it takes a massive amount of energy to awaken Majin Buu, Babidi decides to use theirs. Dabura is ordered to kill all but Supreme Kai and the strongest three, and lure the remainder inside the ship. Dabura obeys and quickly charges the group, despite them hiding their Ki. With a single blast, he kills Kibito. He then quickly leaps in the air and spits on Piccolo and Krillin, turning them into stone, with Supreme Kai explaining the only way they can turn back is if Dabura dies. Dabura then retreats back into Babidi's spaceship, telling the brave Saiyans to wander into their domain if they dare.
Dabura joins Babidi in a monitoring room and watches as the Z Fighters and Supreme Kai enter the spaceship, being greeted by Pui Pui. Vegeta easily kills Pui Pui, and then watches Goku destroy Yakon, before Dabura himself emerges to confront Gohan on the third floor. When first encountered, Goku mentions that Dabura's Power Level is comparable to that of Perfect Cell. Though initially it seems that Gohan and Dabura are even, Goku corrects himself and states that Dabura might be stronger than he once thought, with his usage of magic and several tricks.
During his battle with Gohan, Dabura takes notice of Vegeta's poor temperament and his one-track mind for settling things with Goku, which gives Dabura an idea. Dabura then retreats from the fight with Gohan in order to inform Babidi of Vegeta's evil in his heart. Babidi quickly takes advantage of that information and possesses Vegeta, when this was actually what Vegeta wanted all along, so he would gain a greater power and finally defeat Goku.
With Vegeta (after refusing to kill the Kai and Gohan, stating that they're of no interest to him) now battling Goku, Dabura stands with Babidi to fight against Supreme Kai and Gohan. Before they can start though, they are all shocked as the energy released from Vegeta and Goku's battle has already been enough to release Majin Buu, as both fighters were fighting at Super Saiyan 2, the form thought to be the pinnacle of Super Saiyan states at the time

Information from:
http://dragonball.wikia.com/