Nicholas Merbury (died 1421) was an English administrator, Member of Parliament and first Master of the Ordnance.
He begin his career in the service of Henry Percy, 1st Earl of Northumberland and was present, in September 1402, at the Battle of Humbleton Hill in Northumberland.
After Percy's downfall, he transferred his allegiance to King Henry IV.
He also held a number of other lifetime public appointments such as Usher of the King's chamber (1415), Chief Butler of England (1418), Chirographer of the common pleas (1420), Keeper of the King's jewels and privy purse (1421) and Bailiff of the royal forest of Cliffe, Northants.
Nicholas's estates passed to his brother Sir Laurence, and then apparently to their niece Elizabeth, Lady Devereux.