Descendants are deadlier enemies in Uncharted: Drakes Fortune. They have the appearance of zombie-crawling creatures. They seem to attack anyone that tries to steal the treasure of El Derado. They were in-fact infected by the cursed statue, which made them demons. They killed Eddy Raja in Chapter 17 - The Heart of the vault. Drake had found out that they were cursed by the treasure, so he had to stop the statue from leaving the island, otherwise, Atoq Navarro would have turned everybody into Descendants. Gabriel Roman didn't know about the curse, when Navarro did, it's when he, then, turned into a Descendant as well, after which, Navarro shot him, possibly killing him as well.
Uncharted 2: Among Thieves
In Chapter 6 - Desperate times, Drake muttered, "Great, power's out, and a girl's trapped. I swear to God, if there's a zombie around the next corner..." This could be referring to the time that he had to get the power back on for Elena to get out, while fighting Descendants on the way from and back to the generator.
Uncharted 3: Drake's Deception
Right before Chapter 10 - Historical Research begins, Elena mentions something about, "cursed treasure", which could be referring to the Descendants. Also in multiplayer, when patch 1.13 was released, a Descendant Mask was available for both the Custom Hero and Villain by completing the Decorative Pendants treasure set.
Playstation All-Stars Battle Royale
Descendants also appear during Drake's level 3 super in Playstation All-Stars Battle Royale.