Major-General Thomas Harrison (baptised 16 July 1616 - executed 13 October 1660) was a prominent member of the radical religious sect known as the Fifth Monarchists, and a soldier who fought for Parliament and the Commonwealth in the Wars of the Three Kingdoms.

[1] When the First English Civil War began in August 1642, the Earl of Essex was appointed commander of the Parliamentarian army, and Harrison enlisted in his personal troop of Lifeguards, which was recruited almost exclusively from the Inns of Court.

He plainly told them, when witnesses were produced against him, that he came not thither with an intention to deny anything he had done, but rather to bring it to light, owning his name subscribed to the warrant for executing the King, to be written by himself; charging divers of those who sat on the Bench, as his judges, to have been formerly as active for the cause, in which he had engaged, as himself or any other person; affirming that he had not acted by any other motive than the principles of conscience and justice; for proof of which he said it was well known, he had chosen to be separated from his family, and to suffer a long imprisonment rather than to comply with those who had abused the power they had assumed to the oppression of the people.

So that a hasty verdict was brought in against him, and the question being asked, if he had anything to say, why judgement should not pass, he only said, that since the Court had refused to hear what was fit for him to speak in his defense, he had no more to say; upon which Bridgeman pronounced the sentence.

And that the inhumanity of these men may the better appear, I (Edmond Ludlow) must not omit, that the executioner in an ugly dress, with a halter in his hand, was placed near the Major-General, and continued there during the whole time of his trial, which action I doubt whether it was ever equaled by the most barbarous nations.

[8][9] His head adorned the sledge that drew fellow regicide John Cook to his execution, before being displayed in Westminster Hall; his quarters were fastened to the city gates.

[10] Samuel Pepys wrote an eyewitness account of the execution at Charing Cross, in which Major General Harrison was drily reported to be "looking as cheerful as any man could do in that condition".

This account is also quoted on a plaque on the wall of the Hung, Drawn and Quartered public house near Pepys Street, where the diarist lived and worked in the Navy Office.

Upon hearing his request, Thomas Harrison replied, "I do forgive thee with all my heart... Alas poor man, thou doith it ignorantly, the Lord grant that this sin may be not laid to thy charge."

Samuel Pepys, presumably one of the more refined men of his day, made the following entry in his diary for October 13, 1660: Out to Charing Cross, to see Major-general Harrison hanged, drawn, and quartered; which was done there, he looking as cheerful as any man could do in that condition.

Pepys's cold joke about Harrison's "looking as cheerful as any man could do in that condition" referred to his being partly strangled, disemboweled, castrated, and shown his organs being burned before being decapitated.