Jack William Armstrong
- Bats Right, Throws Right
- Height 6' 5", Weight 215 lb.
- School University of Oklahoma, Rider College
- High School Neptune High School
- Debut June 21, 1988
- Final Game April 17, 1994
- Born March 7, 1965 in Englewood, NJ USA
Before the All-Star break in 1990, Armstrong went 11-3 for the Reds. He was named the starting pitcher in the All-Star Game, but then only won one more game the rest of the season, against six losses. By the time the postseason rolled around, he had been bounced from the starting rotation. He did make one appearance in the 1990 World Series, pitching 3 innings of one-hit relief in Game 2, which the Reds won in 10 innings. He was selected by the Florida Marlins in the 1992 Expansion Draft.
He threw a low-90s fastball, a curve and a slider.