Fallen One

Long before Galactus converted Norrin Radd into the Silver Surfer, he had another Herald named The Fallen One. The biggest difference between the two was their power base. Radd was imbued with the Power Cosmic while The Fallen One was given power thanks to Dark Energy. Another distinguishing factor between the two was that The Fallen One was about as evil as someone could possibly be.

The Fallen One was incredibly powerful, but he became little more than a nuisance to Galactus who preferred not to put up with his former Herald. After sending him away, he found himself a Herald of Thanos: The Mad Titan. Their partnership worked out for a while until The Fallen One was destroyed while fighting a couple of gods for his new boss.