Eleven vessels of the Royal Navy have been named HMS Grampus after two members of the dolphin family (Delphinidae): Grampus griseus, also known as Risso's Dolphin, and Orcinus orca, also known as the killer whale.
- HMS Grampus was a 14-gun sloop launched in 1731. She foundered in the English Channel in 1742.
- HMS Grampus was a 14-gun sloop launched in 1743 and was captured by the French in 1744.
- HMS Grampus was a 14-gun sloop launched in 1746. She was converted to a fire ship and renamed Strombolo in 1775. She was hulked in 1780.
- HMS Grampus was a 70-gun third-rate ship of the line launched in 1751 as HMS Buckingham. She was renamed HMS Grampus in 1777 and used as a storeship.
- HMS Grampus was a 50-gun fourth rate launched in 1782 and broken up in 1794.
- HMS Grampus was a 54-gun fourth rate, originally the East Indiaman Ceres. She was purchased in 1795 and wrecked in 1799.
- HMS Grampus was a 50-gun fourth rate launched in 1802. She was used for harbour service from 1820, became the first of the Seamen's Hospital Society's hospital ships, and was sold in 1832.
- HMS Grampus was a 50-gun fourth rate launched in 1784 as the 74-gun third-rate HMS Tremendous. She was rebuilt in 1810, and renamed HMS Grampus in 1850 and reduced to 50 guns. She served as powder hulk from 1856 and was sold in 1897.
- HMS Grampus was a Beagle-class destroyer launched in 1910 as HMS Nautilus. She was renamed HMS Grampus in 1913 and was sold in 1920.
- HMS Grampus was a Grampus class submarine launched in 1936 and sunk by Italian torpedo boats in 1940.
- HMS Grampus was a Porpoise-class submarine launched in 1957. She was used as a training ship from 1976 until 1979, and was sunk as a target in 1980.