Of all the major story arcs in Dragon Ball Z, the Buu Saga is among the most divisive for its perceived flaws and wasted potential. One such case to be made for the latter is Dabura, the King of the Demon World and Babidi's strongest and most loyal henchman. Despite a simple, memorable design, compelling backstory and some downright dangerous abilities, Dabura is best remembered for dying via transforming into a cookie, courtesy of Majin Buu. Then, specifically in the anime, he comedically reforms into a lovey-dovey soul who befriends Chi Chi, Videl and Bulma in heaven.
Despite being a clear side villain from the start, did Dabura deserve more time in the spotlight? Like Babidi's other Majin fighters, Goku, Vegeta and even Gohan don't take Dabura all that seriously at first. Somewhat justifiably, as Goku and Vegeta overcame their opponents quickly and without giving up any energy to Majin Buu. On the other hand, Dabura had already shown one of his most lethal weapons with his spit turning Krillin and Piccolo into stone. Not to mention murdering Kibito with one energy blast.
Although he was no match for Majin Buu, Dabura gives a solid showing of his abilities during a short, action-packed fight with Gohan. Goku at first estimates Dabura's strength to be around the level of Perfect Cell, but in the manga, he and Vegeta are both forced to admit they underestimated him. Power levels aside, Dabura dealt a fair amount of damage to Gohan and helped gather energy for Buu's release. It's also unlikely Dabura was fighting his absolute hardest in this battle -- Gohan even tells him to power up at one point -- as his objective was strictly to deal physical damage. Killing him outright -- at least early on -- would've been counterproductive to Babidi's plans.
Had Dabura not stopped the fight so he could advise Babidi about the darkness in Vegeta's heart, Vegeta may have tried to take over from Gohan. Both he and Goku were fully confident Dabura could be beaten and, especially in the manga, they show more disappointment than concern at Gohan's struggles. This implies Goku and Vegeta weren't overly worried about the end result, even if one of them would've been forced to step in.
The only time viewers see the King of Demons fighting at maximum strength is against Majin Buu, a battle he was always doomed to lose. It raises an interesting point about Dabura's personality -- as loyal and helpful as he was to Babidi, he immediately sensed that Buu was far too powerful to truly be under Babidi's control. As Babidi callously turns on his longtime ally, Dabura's self-preservation instincts kick in as he tries to kill Buu himself.
In general, the manga gives Dabura more time and love than the anime. He makes a surprise appearance in Dragon Ball Super, when Future Trunks returns and tells the present Z fighters about battling Dabura and Babidi and successfully stopping Majin Buu's resurrection. In the anime, Supreme Kai warned him ahead of time about Dabura's abilities so Trunks was properly prepared for the battle. In the manga, Dabura takes on all of Trunks, Supreme Kai and Kibito by himself and overpowers them, killing Kibito. This triggers Trunks' transformation into Super Saiyan 2, after which he and Supreme Kai work together to destroy Dabura.
For DBZ, naturally, the Buu Saga had to focus predominantly on its titular villain. Especially since that villain had umpteen different forms to go through, with one of them ultimately becoming a good person. On the other hand, surely a character known as the Demon King deserved a less humiliating death than being turned into a cookie and eaten by a fat pink blob. As Frieza, Android 17 and others have shown in Super, however, the series is never afraid to bring old, possibly reformed villains back for new storylines. It would be interesting to see what kind of choices Dabura would make if brought back, and no longer bound by anyone else's control.