John Belasyse, 1st Baron Belasyse was an English nobleman, Royalist officer and Member of Parliament, notable for his role during and after the Civil War. He suffered a long spell of imprisonment during the Popish Plot, although he was never brought to trial. From 1671 until his death he lived in Whitton, near Twickenham in Middlesex. Samuel Pepys was impressed by his collection of paintings, which has long since disappeared.

The Popish Plot was a fictitious conspiracy invented by Titus Oates that between 1678 and 1681 gripped the kingdoms of England and Scotland in anti-Catholic hysteria. Oates alleged that there was an extensive Catholic conspiracy to assassinate Charles II, accusations that led to the executions of at least 22 men and precipitated the Exclusion Bill Crisis. During this tumultuous period, Oates weaved an intricate web of accusations, fueling public fears and paranoia. However, as time went on, the lack of substantial evidence and inconsistencies in Oates's testimony began to unravel the plot. Eventually, Oates himself was arrested and convicted for perjury, exposing the fabricated nature of the conspiracy.