Richard Graham, 1st Viscount Preston PC (24 September 1648 – 22 December 1695) was an English diplomat and politician who sat in the House of Commons in two periods between 1675 and 1689.

His exertions were rewarded by his being created a peer of Scotland by the title of Viscount Preston in the county of Haddington, and Baron Graham of Eske.

The patent, which is dated at Windsor Castle on 12 May 1681, recites that Charles I in 1635 had given the warrant to Sir Richard Graham, the patentee's grandfather, and that it had afterwards been burnt by the rebels.

In August he gave notice that a plot for a descent upon Ireland was being concocted in France against Charles, and he employed spies to collect information on the subject.

In October 1683 the Earl of Sunderland by the king's commands gave Preston directions to let the ministers in France know 'what a very ill man Dr. Burnet was.'

He was ordered to endeavour to trace out Bomeny, the valet to the Arthur Capell, 1st Earl of Essex, who was suspected of being privy to that nobleman's death in the Tower of London.

In conjunction with Lord Middleton he was entrusted by James with the management of the House of Commons which met on 19 May, was sworn a member of the privy council on 21 October, and five days later became chancellor to the queen-dowager.

After the revolution Preston, who was in high favour with Louis XIV, was entrusted by the French government with considerable sums of money for political purposes.

In a gesture, which was also intended to be a test case, James II, created him, by letters patent dated at St. Germain-en-Laye 21 January 1689 Baron of Esk, in the Peerage of England, which title was not recognised subsequently by the House of Lords.

Soon after midnight on 1 January 1691 Preston, Major Edmund Elliott, and John Ashton were seized as they lay concealed in the hatches of a smack making for Calais or Dunkirk.

A packet of treasonable papers, tied together and weighted in order to be sunk in case of surprise, was dropped by Preston with his official seals, and seized upon the person of Ashton, who had tried to conceal it.

He pleaded that as a peer of England he was not within the jurisdiction of the court, but this plea being overruled, he was on 17 January found guilty, and condemned to death two days afterwards.

Lady Preston, on petitioning the queen for her husband's life, received an intimation that he could save himself by making a full discovery of the plot.

Preston employed the remainder of his life in revising for the press a translation with notes of Boethius's De Consolatione Philosophiae which he had made in 1680.