Does anybody know what episode of The Scooby-Doo Show this ghost is from? http://i1236.photobucket.com/albums/ff456/Scooby-Doo2092/Scooby-DooShow_openingghoul.png?t=1301176846
The image is taken from the opening credits...at first I thought that this ghoul was the vanilla ghost from "The Ghost of the Bad Humor Man", but upon closer inspection I found that he doesn't look the same (the ghosts from that episode are recolourings of the phantom shadows from the Where Are You! episode: "A Night of Fright is No Delight").
I've checked a couple of different archives of Scooby villains and this white ghost doesn't appear to be in any of the three seasons. Perhaps this is a bit of unused footage, much like the sequence at the end of Where Are You!'s second season opening in which Scoob emerges from a manhole, wearing a monster mask.