| William James Patterson | |
| Birth Date: | 7 February 1838 |
| Birth Place: | Ireland |
| Death Place: | Pittsburgh, Pennsylvania |
| Office: | Commander-in-Chief of the Grand Army of the Republic |
| Term Start: | 1916 |
| Term End: | 1917 |
| Predecessor: | Elias Riggs Monfort |
| Successor: | Orlando Allen Somers |
William James Patterson (February 7, 1838 – November 6, 1926) was the Commander-in-Chief of the Grand Army of the Republic from 1916 to 1917.[1]
He was born in Ireland on February 7, 1838. By 1860 he had migrated to the United States. He served in the American Civil War and was wounded and captured at the Battle of Gaines' Mill. He served as the Pennsylvania's Department Commander of the Grand Army of the Republic from 1898 to 1899. In May 1913 he was named to an eight-member commission to plan the 50th anniversary commemoration of the Battle of Gettysburg. He was the Commander-in-Chief of the Grand Army of the Republic from 1916 to 1917.[1] He died on November 6, 1926.