Lord John Hay may refer to:

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Brigadier-General Lord John Hay (c. 1668-25 August 1706), second son of John Hay, 2nd Marquess of Tweeddale . Served in the British Army under the Duke of Marlborough; Colonel of the Scots Greys from 1704 to his death.

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Rear-Admiral Lord John Hay (1 April 1788-26 August 1851), third son of George Hay, 7th Marquess of Tweeddale . Royal Navy officer; Fourth Naval Lord , 1846-1847; Third Naval Lord, 1847-1850.

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Admiral of the Fleet Lord John Hay (23 August 1827-4 May 1916), fourth son of George Hay, 8th Marquess of Tweeddale. Royal Navy officer; Fifth Naval Lord , April-May 1866; Fourth Naval Lord , May-July 1866; Third Naval Lord, 1868-1871; Second Naval Lord, 1880-1883; First Naval Lord, 1886; Admiral of the Fleet, 1888.