Scientific American has an article describing how photographs are doctored, something that is much easier today with digital photography. Here are some of the most famous ones throughout history. (hat tip) I don’t think that there is a Jewish figure whose pictures have been doctored as much as those of the late Rebbe of Lubavitch, R. Menachem Mendel (!) Schneerson. Regarding pictures of rabbis see this post. AFAIK the best collection and analysis of Rebbe photographys is Larger Than Life by Rabbi Shaul Shimon Deutsch. Here is one of the easier to spot doctored photographs (hint: look at the kippah).
For more Rebbe pictures see here.