Thomas Dangerfield (ca. 1650 – 22 June 1685) was an English conspirator, who became one of the principal informers in the Popish Plot. He died violently, although whether his killing was murder or manslaughter was a matter of considerable public debate at the time.
Dangerfield was born about 1650 at Waltham Abbey, Essex, the son of a farmer. At the age of about 12 c.1662, he ran away from home to London, and never returned to his home.
He began his career by robbing his father, and, after a rambling life, took to coining false money, for which offence and others he was many times imprisoned: it was said later that to describe his career one need simply list every capital crime known to English law. Lord Chief Justice Scroggs later referred to him with contempt as "that fellow from Chelmsford gaol", and he also spent time in Newgate Prison. He used a number of aliases, most commonly Willoughby.
False to everyone, he first tried to involve James Scott, 1st Duke of Monmouth and others by concocting information about a Presbyterian plot against the throne, and this having been proved a lie, he pretended to have discovered a Catholic plot against Charles II. This was known as the Mealtub Plot, from the place where the incriminating documents were hidden at his suggestion, and found by the King's officers by his information.
Mrs Elizabeth Cellier, in whose house the meal tub was found, was a well- known Roman Catholic midwife and almoner to the Countess of Powis; she had rescued Dangerfield from a debtors' prison and befriended him when he posed as a Catholic. She was, with her patroness Lady Powis, tried for high treason but acquitted in 1680: with the general waning of hysteria, men as disreputable as Dangerfield were no longer considered to be credible witnesses.