Guilford Slingsby (1610–1643) was a member of the Yorkshire gentry who was confidential secretary to Thomas Wentworth, 1st Earl of Strafford, and present during the trial which ended in his execution in April 1641.

When the First English Civil War began in August 1642, he raised a regiment for the Royalist army in Northern England; he was badly wounded in a skirmish near Guisborough on 16 January 1643 and died three days later.

[3] His uncle Sir Francis Slingsby (1559-1651) served in the Nine Years' War in Ireland and married an heiress; he was a member of the Munster Council where he held extensive lands.

[4] The Oxford Dictionary of National Biography states Slingsby was appointed to the Irish Board of Ordnance and Vice-admiral of Munster; the latter position was held by Strafford, so he may have acted as his deputy.

[6] These proved unsuccessful; prior to his execution, Strafford wrote Slingsby a final letter which ended "...God direct and prosper you in all your ways; and remember there was a person whom you were content to call master that did very much value and esteem you and carried to his death a great stock of his affections for you".