William Marvin Watson (June 6, 1924 – November 26, 2017) was an advisor to U.S. president Lyndon B. Johnson and was Postmaster General from April 26, 1968, to January 20, 1969.

He began working for Johnson during the 1948 primary campaign for the Democratic nomination to run for the United States Senate.

Watson continued being active in local politics as a "Johnson Man," rising to become the head of the Democratic Party in Texas.

Johnson called upon Watson to help organize the 1964 Democratic Convention in Atlantic City, New Jersey.

[3] In this position, his workday frequently began shortly after 6:00 in the morning, and he routinely didn't return home for the day until midnight or later; even during his off hours, he remained on call, and quite often found himself back at his desk in the White House on Sundays in order to deal with sudden issues.