Undead Jed is the zombified form of Jed, and the final boss fight of the Eye for an Eyeminiquest. Captured by The Harbinger after seemingly being devoured by Thalassus, Jed was interrogated and tortured for failing to bring back his slave quota, and was zombified as a result, being turned into Undead Jed. Jed feigned being a defective undead so he could escape when the time was right, and fled to Cyclosis to enact revenge against Lookout Ekahi, who had betrayed him. During the miniquest, he takes some of Ekahi's soul in order to bolster his own, and is then killed by the player character.
The battle against Undead Jed has a boss life bar, much like that of Araxxor and similar, but he almost certainly will die in one hit to the player (even unarmed) as he has essentially no defence and only 100 life points.
His examine text is a portmanteau of "zombie" and "Jed".
He calls the player a dairy farmer, whilst the player comments that they aren't trading insults. This is a reference to 'Insult Sword Fighting' in Monkey Island.