But just imagine Bill Murray in frickin Zoombieland. Think about what the movies were going for.
Harold and Kumar is an over the top comedy full of exaggerations. NPH makes sense in the film, yeah it was funny, but its not a big curveball nor is it a real representation of him.
Bill Murray in Zombieland is gold. How can you imagine in a post-apocalyptic zombie world that out of all the people you'd run into, it would be Bill Murray and he's exactly how you'd want him to be. Reenact ghostbusters, he makes fun of his past projects (garfield) and plan a prank with him on one of your friends.
Bill Murray >NPH ...It's realistic and true to Bill Murray. NPH was a fake NPH personality and wasn't as big of a surprised in relation to the storyline.
Honorable mention--Ben Affleck and Matt Damon in Jay and Silent Bob Strike Back filming Good Will Hunting 2: Hunting Season. Extra kudos to Affleck for the cameo and playing another role in the same movie.