Known as the king of the Demon Realm, Dabura was a slave to Babidi's mind control, making him his most powerful subordinate before Majin Buu is resurrected. In his realm, he is by far the strongest fighter alive, and his strength is still frightening in our realm.
Dabura is the king of Demon realm. About thousand years ago he was spelled by evil wizard Babidi. Since then he begun to work on Babidi's task. About 300 years ago of the series timeline, he visited the Earth to look for being of higher power level. As none of the Z fighters were born at that time, he couldn't find any and left. 300 years later he appeared again on Earth with Babidi to free Majin Buu by collecting energy from powerful warriors of the world.
Even under Babidi's control, Dabura's kingly arrogance and personality is maintained. His infamy is widely known, as Supreme Kai shows intense fear at the initial sight of him. After his death, his personality makes a 180 degree shift. He is overly nice and gentlemanly, and he creeps out, Videl, Bulma, and ChiChi in the process.
He was the one responsible for turning Krillin and Piccolo into stone with his spit, and seemingly destroyed Kibito before Goku and the rest followed him and Babidi to their base of operations. He later fought on equal levels with Gohan in a one-on-one match, which was cut short when he took note of Vegeta's evil spirit, seeing another potential servant for Babidi. When Majin Buu is finally brought back, Dabura is disposed of by his master. Seeing Buu as far too big of a threat, Dabura tries to kill him, but fails, as Buu turns him into a cookie to indulge in.
In the afterlife, Dabura is eventually rehabilitated, having been rejected from Hell, given that it was his natural habitat to begin with. He is seen occupying Heaven along with the spirits of Videl, Bulma and Chi Chi, well after Buu's annihilation of the human race.
Dabura is the king of the Demon Realm, and is the most powerful being there. His strength and infamy reaches our realm as well, and he is easily one of the strongest fighters in the universe at the beginning of the Buu Saga, able to easily defeat the less powerful Z Fighters such as Krillin and Piccolo and going toe to toe with Gohan.
He attempts to destroy Buu, but much like everyone else fails to put a dent in him despite his immense power.