ben_danger said:
sounds daft, but i always assumed (before ROTS) that the emperor was just old and ugly in ROTJ, not alien, not facially corrupted by evil, just OLD. i mean he has to be in his 60s in ROTS, so mid to late 80s in ROTJ right?

Sure that would account for some of his look, but not all of it, the eyes, the skin and the strange forehead are not a sign of him just being old.

The Dark Side eating away at him would account for the rest much better than the Force lightning thing which never effected anyone else that bad (Luke gets several full blasts, Palpatine gets no more than he does and it's reflected so presumably weakened. Why then isn't Luke all saggy?).

Back in the day I thought he might be very, very old (200 or something) which now doesn't chime with the prequels as we see them (unless there is a Dorian Gray aspect to his use of the Force which was somehow broken in his conflict with Mace).