HMS Hamadryad was a 46-gun fifth-rate Modified Leda-class frigate of the Royal Navy.

In February 1866 she was designated for handing over to Messrs. Marshall, the shipbreakers, to be taken to pieces, but instead on 9 March 1866 it was decided to lend her as a floating hospital for sick seamen in Cardiff.

[1] Finally in 1900, she was returned to naval control and transferred to Portsmouth, where she was sold for breaking up on 11 July 1905.

[1] The site of her mooring is now a Welsh Medium Primary School (opened January 2019), taking its name (Ysgol Hamadryad).

[2] Another redundant Leda-class frigate, HMS Thisbe, was also moored in Cardiff and used as a floating church by the Missions to Seamen on from 1863 to 1891.