William Monsell, 1st Baron Emly, PC (21 September 1812 – 20 April 1894)[1][2] was an Anglo-Irish landowner and Liberal politician.

He held a number of ministerial positions between 1852 and 1873, notably as President of the Board of Health in 1857 and as Postmaster General between 1871 and 1873.

[1][2] As his father had died in 1824, he succeeded to the family estates on coming of age and was a popular landlord, the more so as he was resident.

His work being chiefly parliamentary, he wrote little, but published some articles in the Home and Foreign Review and a "Lecture on the Roman Question" (1860).

He married firstly Lady Anna Maria Charlotte Wyndham-Quin (1814–1855), only daughter of Windham Quin, 2nd Earl of Dunraven and Mount-Earl, in August 1836,[1] with whom he had two sons, both of whom died in infancy.