Simon John Manley CMG (born 18 September 1967) is a British diplomat, now the UK Permanent Representative to the WTO and UN in Geneva and previously Ambassador to Spain from October 2013 to August 2019.

Before his posting to Madrid, he served as Director Europe at the FCO (2011-2013), responsible for policy toward the EU.

He has been posted to the UK's Mission to the United Nations in New York City (1993-1998), where he worked on Yugoslavia and UN reform, and has twice been seconded to the European Union: to the European Commission (2003) and to the Council of the EU (1998-2002).

In March 2020 Manley was appointed Director-General for COVID-19 at the Foreign & Commonwealth Office, leading and coordinating HMG's coronavirus rollout.

Manley and Clara Manuela da Luz Delgado Jesus were new, joining El Salvador's Ana Patricia Benedetti Zelaya, as co-chairs of the Working Group.