Sir William Moore, 1st Baronet, PC (NI), DL (22 November 1864 – 28 November 1944) was a Unionist member of the British House of Commons from Ireland and a Judge of Ireland, then of Northern Ireland. He was created a Baronet (of Moore Lodge, Ballymoney, County Antrim, Northern Ireland) in 1932.
Sir William was the eldest son of Queen Victoria's honorary physician in Ireland, Dr. William Moore of Rosnashane, Ballymoney. His ancestors came to Ulster during the Plantation, settling at Ballymoney, at which time they were Quakers. The Moore Lodge estate was inherited from a relative; the family owned several other houses: Moore's Grove and Moore's Fort. Sir William Moore's mother was Sidney Blanche Fuller. In 1888 he married Helen Wilson, the daughter of a Deputy Lieutenant of County Armagh. Sir William went on to become a Deputy Lieutenant for County Antrim and a Justice of the Peace.
Sir William was schooled at Marlborough College, then attended Trinity College, Dublin, where he was President of the prestigious University Philosophical Society. He was called to the Irish Bar in 1887, to the English bar in 1899, and became an Irish Queen's Counsel the same year. He was a Member of Parliament, representing North Antrim 1899–1906. During this period he was an unpaid secretary to the Chief Secretary for Ireland 1903–1904.