Joseph Leeson, 1st Earl of Milltown (11 March 1701[1] – 2 October 1783) was an Irish peer and politician.

His grandfather Hugh Leeson of Culworth in Northamptonshire came to Ireland about 1680, as an officer in military service, and made a fortune as a brewer, acquiring much property in the area around what is now Dawson Street.

The Earl had one known sibling – his sister, Joyce Leeson, who married Sir Robert Blackwood, 1st Baronet, the ancestor of the Barons Dufferin and Claneboye).

Lord Milltown commissioned Russborough House, a particularly fine example of Palladian architecture, designed by Richard Cassels and built between 1741 and 1755.

The interior of the house contrasts with the austere exterior by way of some ornate plasterwork on the ceilings by the Lafranchini brothers.