| Image Name: | William J. Green, Jr. (Pennsylvania Congressman).jpg |
| State: | Pennsylvania |
| District: | 5th |
| Term Start: | January 3, 1949 |
| Term End: | December 21, 1963 |
| Preceded: | George W. Sarbacher Jr. |
| Succeeded: | William J. Green III |
| Term Start2: | January 3, 1945 |
| Term End2: | January 3, 1947 |
| Preceded2: | C. Frederick Pracht |
| Succeeded2: | George W. Sarbacher Jr. |
| Birth Date: | 5 March 1910 |
| Birth Place: | Philadelphia, Pennsylvania, U.S. |
| Death Place: | Philadelphia, Pennsylvania, U.S. |
| Resting Place: | Holy Sepulchre Cemetery, Cheltenham Township, Pennsylvania, U.S. |
| Spouse: | Mary Kelly |
| Children: | 6, including William III Anne Green Michals |
| Relatives: | Bill Green IV (grandson) |
| Party: | Democratic |
| Alma Mater: | St. Joseph's College |
| Allegiance: |  United States |
| Branch: | United States Army |
| Serviceyears: | 1944 |
| Rank: | Private |
William Joseph Green Jr. (March 5, 1910 - December 21, 1963) was a Democratic member of the U.S. House of Representatives from Pennsylvania.
William J. Green was born in Philadelphia, Pennsylvania, the son of Irish immigrants. He graduated from St. Joseph's Preparatory School, and attended St. Joseph's College in Philadelphia. He was engaged in business as an insurance broker in Philadelphia in 1937. He served in the United States Army as a private in the Quartermaster Corps from March 22, 1944, to December 4, 1944.
He was elected to Congress in 1944, and after a defeat in the Republican landslide year of 1946, was reelected to Congress in 1948 and every two years thereafter until his death at age 53. He had been elected Democratic City Chairman in 1953, and, in that role, held until his death, he helped solidify Philadelphia as a Democratic stronghold.
Green died of peritonitis and gall bladder complications in Philadelphia on December 21, 1963[1] and was interred at Holy Sepulchre Cemetery in Cheltenham Township, Pennsylvania.[2] He was succeeded in Congress by his son, William J. Green III, who was 25 years old at the time of his first election, and later became Mayor of Philadelphia.
The William J. Green Jr. Federal Building, at 6th and Arch streets in Philadelphia, is named for him.