I Know Some People Are Really Protective

of great actors in seminal roles, but I am still willing to have an open mind regarding casting, often thinking 'what would it have been like if ______ played that role?'
Under John's bio, in the trivia it says:

Was considered for the role of Hannibal Lector in The Silence of the Lambs (1991)
Was considered for the role of Doc Brown in Back to the Future (1985). The role went to Christopher Lloyd instead.

While I of course loved both of those iconic roles as delivered to us by the well known actors who played them, I think John would have given a great (if somewhat different) performance in either.

For the Lector one, if anyone doubts John's ability to do insane AND creepy, there's always the closing scene of Raising Cain *shudder*