As a quick rule of thumb, characters aren't part of worldbuilding, much less actors playing the characters. As such, we're probably not the best place for paying tribute to Leonard Nimoy. This is not because we dislike him. As a group, I expect most of us are rather fond of his work, particularly as Spock.
If you're looking purely for a Nimoy related question, perhaps something like
How would the world need to be different for the predominant (humanoid) race to have green blood?
I want to create a a world where the inhabitants look essentially human but have green blood (like the Vulcans on Star Trek). What would have to change to make this happen? Would it be as simple as replacing iron in the blood with something like copper or gold? Or would we need to make more changes for this to make sense?
You could always post in the sandbox if you wanted to try to tweak a question into proper shape.
It would be really difficult to come up with a question that more directly links the actual character of Leonard Nimoy or even his acting skills to actual worldbuilding. It's a touching tribute but not really appropriate for this site. We don't deal with casting decisions. Our focus is on helping people design backgrounds for their stories that are logically (and sometimes scientifically) consistent. By the time that people are on to casting (assuming they are writing a screenplay or play), our job is done. It's up to them to provide ambiance, etc. that can be provided by good acting, lighting, and proper settings.
Perhaps you are correct in describing the thing that you want to discuss as world building, but it's not the kind of worldbuilding that we do here. Your question simply doesn't fit.