William Douglas Wallach (1812 – December 1, 1871) was an American surveyor and newspaper entrepreneur.
Born in Washington, D.C., he earned a civil engineering degree at Columbian College and moved west doing survey work, reaching the Republic of Texas in 1838 where he supported Sam Houston and the annexation of Texas to the U.S.
In 1853 he purchased a stake in the Washington Daily Evening Star, becoming its sole owner in 1855.
He guided it to become one of the city's leading newspapers until 1867, when he sold his interests in the Star to the Noyes, Kauffman, and Adams families.
The Scottish spelling came from his mother and grandmother's family and he was called "Doug".