1. Sandy Koufax- he had one of, if not the most dominating stretch for a pitcher in the history of the game between 1963-1966. I have seen video of him, and he is the best I have ever seen. It's sad that his career ended with arthritis.
2. Roger Clemens- Had a great World Series record and is the only guy to strikeout 20 guys in a game twice in his career. To me, he is really the consumate RH pitcher.
3. Randy Johnson- I'm kind of surprised that he hasn't been mentioned yet. The guy just terrorized hitters. And he was a throwback because he could also close games in an emergency situation from time to time. I mean, hitters in an All-Star game wanted no part of him- the MAJOR LEAGUE All-Star game.
4. Bob Gibson- Speaking of terrorizing hitters. An ERA of 1.12 is just ridiculous. This guy is a big reason why the mound was lowered. Then he goes out and has an 18 K game in the World Series. He was also a great hitter- I think he it something like 6 home runs one year, and he also briefly played for the Harlem Globetrotters as well, I believe.
5. Nolan Ryan- What would his numbers have been if he had played on GOOD teams? I don't know that he would get to Cy Young's 511, but I could see 400. Still, 5,000 K's is pretty awesome and equally as untouchable as Young's win total. I think he had seven no-hitters- and how many guys that are over 40 that you could legitimately say "He could throw a no-hitter tonight"?
Closer- By the way this is my all-time favorite position in baseball, and what I would want to play if I was blessed enough to make it to the Big Leagues. I've got to go with Mariano Rivera as well. He has the cool entrance with Enter Sandman. He might get the all-time saves record- depending on what Trevor Hoffman does, and if he can outlast him. Regardless of whether he gets the save record or not, no one is better in the postseason. I might be a little biased because I share the same birthday as him, and as a side note he is also a big time Christian and he has a really good devotional out.
Edit to say- I see where a couple of people did pick Randy Johnson.