(As far as hollywood characters...
There will always be only ONE James Bond...Sean Connery
...and yet, there will always be only ONE Simon Templar, Roger Moore
...and yet, there will always be only ONE Doc Holliday, Val Kilmer...)
What about Superman? Batman?
I’d probably go Christopher Reeve and Michael Keaton, but I haven’t watched the newer iterations...or read the comic books when I was a kid.
Adam West IS Batman.
Only one Sherlock - Jeremy Brett.