Blood, Thomas (1617/1618–1680), conspirator and spy, was born in Sarney, Co. Meath, the son of a relatively prosperous blacksmith and ironworker, probably also Thomas Blood, from whom he may have inherited the lands he later held at Sarney and in Co. Wicklow. He appears to have had at least one sister, who was married to the Rev. William Lecky (qv). He probably served as a soldier in the 1640s and 1650s, perhaps with the rank of lieutenant, though the details of his service are unclear, and he was later to use the title ‘colonel’. On 21 June 1650 he married Mary, daughter of John Holcroft of Lancashire; they had at least four (and possibly five or six) sons and two daughters. From at least September 1662 he was involved in, and may have led, a plot to seize Dublin castle in opposition to the religious and land policies of the restoration regime. He escaped when many of his co-conspirators, including Lecky, were arrested a few days before the planned coup in May 1663.
Travelling in disguise in England, Ireland and Scotland and on the continent, he retained an involvement in radical conspiracies throughout the 1660s, though it has been suggested that he worked as a government double agent. In December 1670 he led an assault on James, duke of Ormond (qv), in London, perhaps intending assassination, and possibly in collusion with Ormond's political rivals. On 9 May 1671 he was in charge of an attempted theft of the crown jewels from the Tower of London, but he was captured. He was permitted an interview with Charles II which resulted not only in a pardon but in an enhanced re-grant of his Irish property, confiscated after the 1663 plot. A government intelligence agent in the 1670s, he also dabbled in shady court faction fighting, resulting in his imprisonment in January 1680 for slander against the duke of Buckingham. He was released in July but died 24 August 1680, in Westminster, aged 62.