One of the longest-serving was HMS Hermes, which spent a total of 58 years in two navies. Since World War II, aircraft carriers have been one of the most important weapons in a military's arsenal.

Summary: The HMS Hermes, a Centaur-class aircraft carrier, served the Royal Navy from its completion in 1959 until it was decommissioned and sold to India, where it served as INS Viraat until 2017.