HMS Audacious is the fourth Astute-class nuclear-powered fleet submarine of the Royal Navy. Several previous vessels of the Royal Navy have borne the name. She was formally named on 16 December 2016 and was launched on 28 April 2017. Audacious was stated to be handed over in January 2021. A parliamentary written answer stated that Audacious was commissioned on 3 April 2020, but her public ceremonial commissioning took place on 23 September 2021.