H.M.S. Royal Oak
- Class: Royal Oak - 1 wooden broadside ironclad of 1859
- Displacement: 6,366 tons
- Dimensions: 273 x 58 x 25 ft.
- Machinery: Maudslay, Son & Field horizontal single-expansion
steam engine, single shaft = 12.5 knots; sailing speed = 13.5 knots
- Armor: 3-4 in. wrought iron over oak
- Armament: 11-7 in. muzzle-loading rifles, 24-68 pdr. smoothbores
- Builder: Royal Navy Dockyard, Chatham, England
- Laid Down: 1860
- Launched: 10 Sep 1862
- Completed: Apr 1863
- Notes: Begun as a 91-gun two-deck steam ship-of-the-line.
Converted to armoured frigate, cut down to one-deck and lengthened 21 ft.
- Service: With Channel Fleet on completion, then joined the
Mediterranean Fleet until 1867. Returned to Channel Fleet, where she had
a collision in dense fog with HMS Warrior.
After repairs, she was again assigned to the Mediterranean in 1869.
Returned to Portsmouth 1871 and was laid up for economy. Scrapped 1886.