Rear Admiral John Toup Nicolas RN CB KH (1788–1851) was a Royal Navy officer.
Nicolas was born in East Looe, Cornwall. He entered the Royal Navy in 1797 and later served on various ships, including HMS Edgar, HMS Malta, and HMS Queen. As a lieutenant, he participated in the 3rd Battle of Cape Finisterre in 1805. Nicolas commanded several successful attacks while in charge of HMS Pilot, earning praise from the British press. He was promoted to Captain in 1815 and later commanded HMS Egeria, HMS Hercules, HMS Belleisle, and HMS Vindictive. Nicolas was appointed Superintendent of the Victualling Yard at Plymouth in 1847 and retired as Rear Admiral in 1850. He died in Plymouth and is buried in St Martin's Church there.