| William Joseph Guste Jr. | |
| Nationality: | American |
| Office: | Louisiana Attorney General |
| Party: | Democrat |
| Term Start: | May 9, 1972 |
| Term End: | January 13, 1992 |
| Governor: | Edwin Edwards (1972–1980; 1984–1988) Dave Treen (1980–1984) Buddy Roemer (1988–1992) |
| Preceded: | Jack P. F. Gremillion |
| Succeeded: | Richard Ieyoub |
| Office2: | Louisiana State Senator from Orleans Parish |
| Term Start2: | 1968 |
| Term End2: | 1972 |
| Preceded2: | At-large election of eight senators |
| Succeeded2: | Fritz H. Windhorst |
| Birth Date: | 26 May 1922 |
| Birth Place: | New Orleans, Louisiana |
| Death Place: | New Orleans |
| Occupation: | Attorney; businessman |
| Alma Mater: | Jesuit High School Loyola University New Orleans Loyola University New Orleans College of Law |
| Allegiance: | United States |
| Battles: | World War II in France |
William Joseph Guste Jr. (May 26, 1922 – July 24, 2013) was an American attorney and politician from the state of Louisiana. He was Attorney General of Louisiana from 1972 to 1992.[1]