Reds:
Hersh Freeman -Reliever out of Alabama who toiled for the Reds in the mid-to-late 1950s.
Jack Quinn -Was in the news recently when Jamie Moyer surpassed him as the oldest pitcher to win a major league game. Quinn still holds a number of "oldest player" records: oldest player to start a World Series game, oldest pitcher to start on Opening Day, oldest American Leaguer to hit a home run. He wrapped up his career with the Reds in 1933, and you guessed it, he's the oldest player ever to appear in a Reds uniform. He and Hoyt Wilhelm are the only players to play significant roles for their teams after age 50 (the others were "stunt" appearances by Minoso, Altrock and Satchel). In his career, Quinn was a teammate of 31 Hall of Famers.
Others:
Craig Anderson (74) -In 1961 he was a nice little pitching prospect for the Cardinals. Then he was picked in the expansion draft by the Mets, and his career went through the looking glass. On May 12, 1962 he won both ends of a doubleheader. He then proceeded to lose his next 16 games to finish at 3-17. He did manage to lead the '62 Mets in saves (with a grand total of four).
Frank Bauman -Big lefty who was supposed to be the next Herb Score...According to BaseballReference, the 1964 trade that sent him from the White Sox to the Cubs was the first crosstown trade ever between the two clubs. It's hard to believe that the two clubs never traded with each other before 1964, but who am I to question BaseballReference?
John Clarkson -19th-century ace pitcher, a HOFer...He had two brothers who pitched in the bigs, together they're the third-winningest brothers of all time, behind the Perrys and the Niekros...Once pitched a lemon to home plate in an effort to convince the ump to call the game because of darkness. When the umpire was shown that he couldn't tell the difference between a baseball and a lemon, he went ahead and called the game.
Roger Connor -At 6'3" a huge man for 19th-century baseball; he was one of the players that got the New York team the nickname "Giants"...Held the record for career home runs for 26 years before Babe Ruth arrived on the scene...Is credited with hitting the first grand slam in history; what made it even better was that it was a walk-off shot with his team down three runs in the bottom of the ninth.