| Joseph Leo McGlynn Jr. | |
| Office: | Senior Judge of the United States District Court for the Eastern District of Pennsylvania |
| Term Start: | February 14, 1990 |
| Term End: | February 23, 1999 |
| Office1: | Judge of the United States District Court for the Eastern District of Pennsylvania |
| Term Start1: | March 8, 1974 |
| Term End1: | February 14, 1990 |
| Appointer1: | Richard Nixon |
| Predecessor1: | Thomas Ambrose Masterson |
| Successor1: | Harvey Bartle III |
| Birth Name: | Joseph Leo McGlynn Jr. |
| Birth Date: | 13 February 1925 |
| Birth Place: | Philadelphia, Pennsylvania |
| Death Place: | Cancún, Mexico |
| Party: | Republican |
| Education: | University of Pennsylvania Law School (LL.B.) |
Joseph Leo McGlynn Jr. (February 13, 1925 – February 23, 1999) was a United States district judge of the United States District Court for the Eastern District of Pennsylvania.
Born in Philadelphia, Pennsylvania, McGlynn saw action in the United States Navy during World War II, serving from 1943 to 1946. Returning from military duty, he attended Mount St. Mary's College in Emmitsburg, Maryland, receiving a Bachelor of Science degree in 1948 and a Bachelor of Laws from the University of Pennsylvania Law School in Philadelphia in 1951. He was an Assistant United States Attorney in Philadelphia from 1953 to 1960. He worked in private practice in Philadelphia from 1960 to 1965. In 1962, he ran in a special election as a Republican to represent the 10th district on Philadelphia City Council, but lost to Robert B. Winkelman. McGlynn was a judge of the County Court of Philadelphia from 1965 to 1968 and a judge of the Court of Common Pleas for the First District of Pennsylvania from 1968 to 1974.
McGlynn was nominated by President Richard Nixon on January 31, 1974, to a seat on the United States District Court for the Eastern District of Pennsylvania vacated by Judge Thomas Ambrose Masterson. He was confirmed by the United States Senate on March 1, 1974, and received his commission on March 8, 1974. He assumed senior status on February 14, 1990. His service terminated on February 23, 1999, due to his death in Cancún, Mexico.