Richard Llewellyn-Davies, Baron Llewelyn-Davies (24 December 1912 – 27 October 1981) was a British architect.
Llewelyn-Davies was Professor of Architecture at the University College London from 1960 to 1969, and Professor of Urban Planning and Head of the School of Environmental Studies from 1970 to 1975. He was the designer of Milton Keynes, Buckinghamshire.
On 16 January 1964, he was created a life peer with the title Baron Llewelyn-Davies, of Hastoe in the County of Hertfordshire.
He was married to Patricia Parry, having three children. As his wife was made a life peeress, they were one of the few couples who both held titles in their own right.
In 1960, Richard Llewelyn-Davies and John Weeks formed the architectural and planning practice Llewelyn-Davies Weeks, which became one of the most influential hospital design and master planning companies in the UK. Major early commissions included the design of Northwick Park Hospital and the master planning of Milton Keynes.