Political and social activism
Sheen is known for political and social activism. Examples include campaigning against high-cost credit agreements, crises in local journalism and describing himself as a not-for-profit actor due to his contributions to social causes.
On 18 October 2013, Sheen wrote an open letter to the people of Newport, published in the South Wales Argus newspaper. In the letter he condemned the "absurd and tragic" demolition of the Chartist Mural. On 2 November 2013, he spoke at a conference in Newport, and was invited by city council leader Bob Bright to advise a committee on a proposal to replace the mural. Six years later, on 4 November 2019, exactly 180 years after the Newport Rising, a replica mural was unveiled in Newport.
On 24 February 2015, the 175th anniversary of the Chartist Rising in Newport, Sheen made the BBC Cymru Wales's documentary Michael Sheen's Valleys Rebellion. In it, he retraced the journey of 20,000 Chartists who walked from the Gwent Valley to the centre of Newport. In it he explored Welsh attitudes to politics and social change in 2014, and why ordinary people and politicians seemed so far apart. The programme was nominated for Best Single Documentary and Sheen himself was nominated for Best Presenter at the 2015 BAFTA Cymru Awards. It was also nominated for a Torc Award at the 2016 Celtic Media Festival.
On 1 March 2015, Sheen joined the People's March for the NHS in Tredegar, the birthplace of the founder of the NHS Aneurin Bevan, and gave a speech on the importance of the NHS and the welfare state to a civilised, equal and compassionate society, opposing the privatisation of the NHS and opposing Conservative's austerity cuts to the UK's health service. His NHS speech went viral, with many posting and sharing clips of him speaking at the march, lauding him as "an upcoming face in politics". When asked by BBC News if he was surprised by the reaction to the speech, Sheen said: "I didn't know it was being filmed. It was a cold and very wet day. The fact that anyone turned up at all was amazing and that they stayed around was amazing." Sheen also told BBC News that he was not affiliated to any political party and that "they're all doing terrible jobs on the whole", but that he would still speak out about what he witnessed whenever he got the chance.
On 21 December 2015, Sheen started a petition calling on the Welsh Government to put an end to homeless teenagers being put into unsuitable bed and breakfast accommodation on Change.org following news of young people being murdered while staying in B&Bs with potentially dangerous ex-offenders. The petition raised more than 115,000 signatures and Sheen presented the issue directly to the Minister for Communities and Tackling Poverty Lesley Griffiths, who announced in March 2016 that the Welsh Government had issued stricter statutory guidance to local authorities to stop the use of B&B accommodation for 16 and 17 year olds once and for all.
On 8 June 2016, the documentary Michael Sheen: The Fight for My Steel Town was broadcast on BBC One Wales, in which Sheen returned to Port Talbot, the town where he grew up, to see for himself the impact on families of hundreds of jobs lost at the steelworks. Michael Sheen: The Fight for My Steel Town won BAFTA Cymru for News and Current Affairs.
On 3 June 2017, Sheen delivered his Aneurin Bevan Lecture at Hay Festival 2017 about "culture and society and the humane vision and tradition that Bevan inspires".
On 16 November 2017, Sheen spoke at the Annual Raymond Williams Memorial Lecture organised by Learning and Work Institute Wales and Open University in Merthyr, Wales. His lecture "explored themes of Welsh culture and identity, its past and its present and to look again at the question Williams once asked – Who speaks for Wales?", Brexit, the decline of local journalism in Wales, and the environmental threats to Wales from PCBs pollution near Brofiscin Quarry reported by researcher Douglas Gowan. Sheen learned about Gowan's studies when he first read an article on Wikipedia, and was then invited to visit and record a seven-hour interview as evidence for his testimony.
He has made calls for discussions about Welsh independence and has made comments about the institution of the "Prince of Wales" title.
On 8 March 2018, Sheen participated in CARE International UK's March4Women on International Women's Day. He paid tribute to suffragist and first Leader of the Labour Party, Keir Hardie and made a speech calling for gender equality.
In July 2022, Sheen made a documentary with BBC Wales Investigates called Michael Sheen: Lifting the Lid on the Care System about the experiences of children in care and found that homeless young people are still staying in B&Bs and sleeping rough, six years after the Welsh government said it wanted to eradicate the practice.
In September 2022, Sheen's stirring motivational speech for the Wales national football team ahead of the 2022 FIFA World Cup on A League of Their Own went viral. He was then invited into the Welsh camp's inner circle to deliver a team talk to coach Rob Page and the players.
In January 2024, Sheen showed support to a cross-party campaign of Plaid Cymru and Welsh Labour focused on devolving the Crown Estate to Wales.
In May 2024, Sheen joined series 2 of BBC Radio 4's award-winning podcast Buried, called Buried: The Last Witness, as the hearsay witness who recorded dead witness Douglas Gowan's final testimony. Together with presenters and investigative journalists Dan Ashby and Lucy Taylor, Sheen conducted a field investigation in South Wales and discovered the lasting impact of 'forever chemicals' on the environment, food chain and communities, and issued a warning for the future. The television documentary Buried with Michael Sheen, exposing the manufacture of PCBs by Monsanto in Newport and their dumping of large amounts of toxic industrial waste, was broadcast on BBC Two across two weeks in August 2026.
In October 2024, Sheen called for a Fair Banking Act to help tackle the unaffordable credit crisis in the UK. On 10 March 2025, in his Channel 4 documentary Michael Sheen's Secret Million Pound Giveaway, he paid off the debts of 900 people in South Wales using his own money while continuing to call on the UK government to enact the Fair Banking Act.
In 2025, Sheen became ambassador for Calon Afan - a community interest company researching and promoting the lesser-known histories of Port Talbot and the Afan Valley.
In 2026, Sheen expressed support for Plaid Cymru in the 2026 Senedd Election, saying that the election "seems to be a battle between, [...] Plaid Cymru and Reform" and when asked directly about if he was supporting Plaid Cymru he said he was.
