Following on from this, which was itself following on from this, comes the idea of playing yourself in an RPG.
And it's a short step to playing other real people. It is for me anyway, because the last time I tried this trick the players got the idea to trade roles and play each other.
For a group with less familiarity and less willingness to take the mickey out of each other, a safer option might be to run with the Celebrity Historical in a slightly unusual manner - with some or all of the PCs as historical figures.
I'm not alone in this notion, of course. Joan of Arc was an example PC in one of FASA's Doctor Who adventures, and in a more extreme example Pacesetter Games produced a TimeMaster adventure book where Boudicca, Amelia Earhart, Cleopatra, Miss Marple, Robin Hood, Merlin, Sgt. Rock and Hercules had to team up to save reality. None of the men are definitely real figures in history, but never mind.
Ms. Earhart was also nearly a companion in one of the never-made incarnations of the Doctor Who movie in the 90s, which is why she ended up meeting the PCs in The Door In Time when they visited The Shadow Proclamation. I erred on the side of "printing the legend" when portraying her as she was a throwaway extra, unlike the more central portrayal of Alan Turing in a previous episode, more like Churchill in Victory Of The Daleks than Van Gogh in Vincent And The Doctor.
Example: The Key
New England, 1766. A colony close to revolution, and a scientist close to a discovery that will change the world even more. And the TARDIS crew must stop an alien intelligence destroying both before they can happen. If humanity fails to harness electricity all of its history will be unwritten, so Benjamin Franklin joins the adventure to save the future.