Everyone knows Captain Kirk and Mr. Spock and of course Scotty, McCoy and Uhura. For those of you who have seen those actual episodes of TOS you probably also remember the really cheap sets and those cheap and sometimes ugly costumes as well. Frankly it was before I was born, so I don't really remember them when they were first aired, but I do remember them when I saw the reruns decades later.
However, my fondest memories of The Old Series crew was not from the series itself, but rather from the movies created later. Personally I loved all of them (except Star Trek V).
Star Trek: The Motion Picture had beautiful artistic license. Plus we got to see a side of Spock that was not normally seen. Seeing the enormous size of the V-Ger probe was astounding.
Star Trek:II The Wrath of Khan tied up some important things that I guess the series had left out about Khan (plus I think many people wanted to see a villain like Khan again.)
Star Trek: III The Search for Spock HAD to be created because many fans could not deal with the fact of Spock's death at the end of Star Trek II. (I think Spock's character was more well loved than even Kirk but who knows for sure).
Star Trek IV: The Voyage Home is my personal favorite. NOT because it's about saving whales... (although I care about that too) but because it was so hilarious! I mean some seriously great comments (satire) was made about our modern society. For example, how we swear all the time, the fact that we are "still using money", and McCoy thought we were living in the dark ages as far as medicine was concerned.
Star Trek V: The Final Frontier was not the best Movie done by far. It was all about Spock's half-brother Sybok and his desire to see what was at the center of the galexy and that he would supposedly find GOD there... the whole time I was saying to myself, "yeah, right" to me it seemed very far fetched.
Star Trek VI: The Undiscovered Country was a very good movie which even my own mother enjoyed in spite of the fact that she's not a Star Trek fan at all. This movie explored moving into new territory no matter what kind of territory that might be. However at the time the movie was made, it really represented our no longer being enemies with the Russians.
These are the six main movies made solely based on The Old Series. However there was one more move made with both The Old Series and The Next Generation crew called: Star Trek: Generations. This brought both crews together and in a way merged the two series together. It was a great movie mostly covering the theories about time travel, death, immortality etc. together.