Sir William Frederick Coates, 1st Baronet, DL, JP (1866 – 19 January 1932) was an Irish stockbroker and politician in Belfast.

He was chairman of the finance committee from 1917 and was elected Lord Mayor of Belfast in 1920 and then re-elected twice, serving until 1923.

He hosted the King and Queen when they visited Belfast to open the Parliament of Northern Ireland (of which he was also a Senator, both ex officio as Lord Mayor and as an elected member 1924-1929[3]) in July 1921.

For hosting the monarchs, and guiding Belfast past the sectarian conflict that marked the creation of Northern Ireland in the early 1920s, Coates was created a Baronet of Haypark.

[6] Upon his son's death in 1994, Sir William's grandson, David Frederick Charlton Coates (b.