HMS Pioneer was a Colossus-class aircraft carrier built for the Royal Navy during World War II.

The ship arrived in Australia in mid-1945 to support operations by the British Pacific Fleet against Japanese forces.

Their design was based on that of the Illustrious-class aircraft carriers, but modified to permit rapid construction in commercial yards.

Steam was supplied by four Admiralty three-drum water-tube boilers operating at a pressure of 400 psi (2,758 kPa; 28 kgf/cm2).

The turbines were designed for a total of 40,000 shaft horsepower (30,000 kW) and gave Pioneer a speed of 25 knots (46 km/h; 29 mph).

[2] The ship carried 3,196 long tons (3,247 t) of fuel oil which gave her a range of 8,500 nautical miles (15,700 km; 9,800 mi) at 11 knots (20 km/h; 13 mph).

[3] In order to maximize space for workshops and stores, the ship's arresting gear and catapult were not fitted; two large deckhouses were added to port of the island and on the rear of the flight deck.

[7] All of the guns were mounted on the flight deck, not in sponsons on the side of the hull like her half-sisters that were completed as aircraft carriers.