I think “irascible and cantankerous” but “with a heart of gold” easily describes the beloved character of Dr. Leonard “Bones” McCoy. Of all the things I like or don’t like about J.J.‘s take on ‘Star Trek’, Bones is definitely in like category. Karl Urban seems to almost channel Deforest Kelly in the ways that matter.
This is a brief character profile video on the good doctor, and it even has just a tiny bit of stuff we haven’t yet seen from the film (that I’m aware of).