STAR TREK nearly always had titles that smacked of a literary bent. Then, admittedly, there were a few like “Spock’s Brain,” but they were the exception.
Via Mona the Monkey: A fairly decent Star Trek TOS third season entry. While the underlying premise was old hat to sci fi fans, the “’world’ is actually a generation starship / conceptual breakthrough” trope was pretty high-concept for 1968 broadcast television.
Trekkie Guy has an online memorial to the numerous actors and other contributors to the original Star Trek series who have died.
Given that the show aired half a century ago, there’s no particular reason to be surprised by the number of entries. But for some reason it’s still a bit unnerving to see pictures of young guest stars whom you vividly remember and then to read they died a few years ago in their 80s.