If Eddie Redmayne had landed the Harry Potter gig, not only would it have possibly derailed any efforts to cast him as the alternate universe Newt Scamander in Fantastic Beasts and Where To Find Them, it might have even altered his career enough that he might have missed out on his Oscar for Best Actor as Stephen Hawking in The Theory of Everything.
Though that hypothetical door works both ways, as Redmayne may have also dodged his role as Balem Abrasax in Jupiter Ascending, so this alternative isn’t without its positive attributes.