No future Astros, only former Astros with birthdays today ~
RHP J.R. Richard (62)
Richard was the Astros 1st round pick (2nd overall) in 1969 and pitched for Houston from 1971 to 1980. When Richard hit his stride, he dominated - leading the National League in ERA in 1979 and leading in strikeouts in 1978 and 1979 with 303 and 313, respectively. He was 3rd in Cy Young voting in 1979 behind Bruce Sutter and Joe Niekro. He was at the peak of his abilities in his 1980 All-Star season with a 10-4 record and a 1.90 ERA and 0.924 WHIP over 17 starts when he was felled by a stroke on July 30th of that year. He was never able to recover his prior success. For more on the fascinating story of J.R. Richard, see his Wikipedia page.
RHP Jose Cano (50)
Cano pitched in 6 games for Houston in 1989, going 1-1 with a 5.09 ERA and a 1.348 WHIP. Cano is father of Robinson Cano. The elder Cano pitched to Robinson in the 2011 Home Run Derby and helped him to win the crown.
IF Jeff Kent (44)
Having signed as a free agent by Houston in December of 2002, Kent played 2B for Houston in 2003 and 2004, hitting .293/.350/.521/.870. Kent was a five-time All-Star and the National League MVP in 2000 while playing for the Giants. He is most remembered by Astros fans for this.