He is seen in The Man Who Would Be King. The demon counterpart of Bobby Singer. Or so as Castiel claims. This demon works for Crowley and organizes the capture of the creatures used for finding that place.
The Winchesters find out from another demon that Ellsworth knew Crowley's location. Castiel goes ahead of them so he can clean the place out before they arrive. This way, they could never get to Crowley. Ellsworth is ended by Castiel.