Famous Persons Not From the Realm of Filmdom Appearing in Movies?

Methinks Bolingbroke Henry IV would be ag'n' it. (as is the Holy Father):

Had I so lavish of my presence been,
So common-hackney'd in the eyes of men
So stale and cheap to vulgar company,
Opinion, that did help me to the crown,
Had still kept loyal to possession
And left me in reputeless banishment,
A fellow of no mark nor likelihood.
By being seldom seen, I could not stir
But like a comet I was wonder'd at;
That men would tell their children 'This is he;'
Others would say 'Where, which is Bolingbroke?'
And then I stole all courtesy from heaven,
And dress'd myself in such humility
That I did pluck allegiance from men's hearts,
Loud shouts and salutations from their mouths,
Even in the presence of the crowned king.
Thus did I keep my person fresh and new;
My presence, like a robe pontifical,
Ne'er seen but wonder'd at: and so my state,
Seldom but sumptuous, showed like a feast
And won by rareness such solemnity.