James Hamilton, 1st Earl of Clanbrassil (c.1618 – 20 June 1659), was an Ulster-Scots Royalist peer, soldier and politician.

Upon the outbreak of the civil war in England, he raised a regiment of foot and a troop of horse in support of Charles I.

[2] Following the defeat of the king by the forces of Parliament, Clanbrassil's estates were seized by Oliver Cromwell.

The marriage, however, never took place, as Mary, despite intense pressure from her formidable father, absolutely refused to marry him, on the unflattering ground that she found him physically repulsive.

Even her father ruefully admitted that he was unable to control "my unruly daughter", and since he was genuinely fond of her he let the betrothal lapse.