(Not likely but they could have seen claymation if they heard about it and really wanted to see it)
- Archduke Franz Ferdinand
Since photography and the zoetrope / other stroboscopic animation techniques existed long before the first known examples of claymation in film, I'm going to amend this list to say that it's theoretically possible the following people could have seen claymation:
- Archduke Franz Ferdinand
- Friedrich Nietzsche