Thomas Whitbread (alias Harcourt) (1618–30 June 1679) was an English Jesuit missionary and martyr, wrongly convicted of conspiracy to murder Charles II of England and hanged during the Popish Plot.

The house in which he and his secretary Edward Mico (who died in Newgate shortly afterwards) had been lodging was part of the Spanish Embassy in Wild Street, but for whatever reason, there was no claim of diplomatic immunity, as there was in the case of some other priests.

Oates testified that he had overheard Whitbread and other senior Jesuits plotting to kill the King in late April 1678 in the White Horse Tavern in the Strand.

This was probably garbled second-hand information about an actual Jesuit meeting which was then going on at Whitehall Palace: but no one corroborated Oates' story, and Whitbread could in good conscience deny the assassination plot, and that he had ever been in the White Horse Tavern.

[8] The importance of the trial is shown by the fact that it was heard by a bench of seven judges, headed by the Lord Chief Justice, Sir William Scroggs, who was a firm believer in the Plot and deeply hostile to Catholic priests.