Sir John Fenwick, 3rd Baronet (c. 1645 – 28 January 1697) was an English Jacobite conspirator, who succeeded to the Baronetcy of Fenwick on the death of his father in 1676. He was involved in a Jacobite plot to assassinate the monarch. He was beheaded in 1697. Life Fenwick was the eldest son of Sir William Fenwick, or Fenwicke, a member of an old Northumberland family. He entered the army, becoming major-general in 1688, but before this date, he had been returned in succession to his father as one of the Members of Parliament for Northumberland, which county he represented from 1677 to 1687. He was a strong partisan of King James II, and in 1685 was one of the principal supporters of the act of attainder against the Duke of Monmouth; but he remained in England when William III ascended the throne in the Revolution of 1688. He had financial problems and in 1688 he sold the rump of the family estates and Wallington Hall to Sir William Blackett for £4000 and an annuity of £2000 a year. The annuity was to be paid for his lifetime and that of his wife, Mary. Blackett was happy with the deal as he discovered lead on the land and he became rich. Fenwick began to plot against the new King William, for which he underwent a short imprisonment in 1689 from May to October. Renewing his plots on his release, he publicly insulted Queen Mary in 1691, and it is practically certain that he was implicated in the schemes for assassinating William which came to light in 1695 and 1696. After the seizure of his fellow conspirators, Robert Charnock and others, he remained in hiding until the imprudent conduct of his friends in attempting to induce one of the witnesses against him to leave the country led to his arrest in June 1696. To save himself he offered to reveal all he knew about the Jacobite conspiracies; but his confession was a farce, being confined to charges against some of the leading Whig noblemen, which were damaging, but not conclusive. By this time his friends had succeeded in removing one of the two witnesses, and in these circumstances, it was thought that the charge of treason must fail. The government, however, overcame this difficulty by introducing a bill of attainder. After a long and acrimonious discussion the bill passed through both