Marvin Jonathan Rees, Baron Rees of Easton OBE (born April 1972) is a British Labour Party politician who served as the second and final Mayor of Bristol from 2016 to 2024. He was created a life peer in February 2025.

Marvin Rees was brought up in Bristol, partly in Lawrence Weston and Easton, by his British mother. He attended St George comprehensive school in Bristol and later obtained a master's degree in political theory and government at Swansea University, and a master's degree in global economic development at Eastern University in 2000. Later he completed the World Fellows Program at Yale University. During a fellowship he assisted Tony Campolo, an advisor to President Bill Clinton.

Rees has worked in diverse areas throughout his career. He was a freelance journalist and radio presenter at BBC Radio Bristol and Ujima Radio. He was the Communications and Events Manager at Black Development Agency (now Phoenix Social Enterprise), an agency devoted to empowering individuals and communities through opportunities to work abroad.

Rees was employed in the city of Bristol as the programme manager for race equality in mental health issues at Public Health, Bristol. He worked in the United States as an outreach assistant at the Sojourners Community and as a youth coordinator at Tearfund.

In 2012, selected by an individual ballot of Labour Party members in the city to stand for Mayor of Bristol, Rees defeated four other candidates for the nomination, including the Leader and Deputy Leader of the Bristol City Council Labour group and a former Member of Parliament, Dan Norris, who would later become Mayor of the West of England. At the election, he received 25,906 votes, coming second, after George Ferguson, an independent. Rees found it difficult readjusting to normal life following his election loss.

In 2012, Rees was the founder and programme leader at the Bristol Leadership Programme, a two-week programme helping a dozen people annually from impoverished backgrounds to attain their aspirations. He was also a member of the Bristol Legacy Commission which dispersed its funds and ceased operating in April 2012. He is a former director of the Bristol Partnership whose goals are to make Bristol's prosperity sustainable, reduce health and wealth inequality, build stronger and safer communities, and raise the aspirations and achievements of young people and families.

Rees was again selected to be the Labour candidate for the 2016 mayoral election, easily defeating a sitting Labour councillor in the selection. On 5 May 2016, he was elected Mayor of Bristol. He received 56,729 votes in the first round and 12,021 transfer votes in the second round, giving him 68,750 votes overall. He then became "the UK’s first directly elected black mayor", and "the first mayor of black African heritage elected in a major European city", so "Bristol became the first major European city to have elected a mayor of black African heritage".

Rees's term of office started with a £30 million budget shortfall inherited from the previous administration and a £60 million budget deficit from government funding reductions to 2020. In August 2016, Rees instigated a voluntary severance programme aimed at reducing the size of the council's workforce from 6,970 by 1,000. Rees commissioned an independent report by former Audit Commission chief executive Steve Bundred, which criticised senior council officers, leading Rees to say a culture of concealment had previously prevailed so councillors were unaware that agreed savings had not been fully delivered.