The Duah, more commonly known as the Ropen, is a flying creature reported from Papua New Guinea. Most reports say it is bat-like or pterosaur-like in appearance. It should also be noted that almost every report claims that the creature glows with light, displaying bio-luminescence. The legend says that it came from the underworld, and when it finds its mate it will take the island down to the underworld to eat his bride alive (hence the name The Underworld Bride). It has appeared in multiple Secret Saturdays commercials, the game Hunt for the Kur Stone.
In the show Zon fell in love with the Duah. The Duah then tried to take her to the underworld to eat her, but Zak Saturday and Ulraj stopped him with help from Ulraj's "shark sense".
In the secret saturdays Beasts of the fifth sun, Zak has to grapple the ropen and swing across them to reach the platforms. They also attack Zak.
The Duah will eat his new bride alive after he takes her to the underworld. It was also known to have eaten fish. It also had a huge pile of human bones in its habitat, meaning that it also ate humans.