Guilherme Castro Boulos (born 1982 in São Paulo) is a Brazilian activist, politician, teacher and author. He is best known as a national coordinator of the Homeless Workers' Movement (Movimento dos Trabalhadores Sem Teto, MTST), a grassroots organisation that campaigns for housing rights and urban reform through occupations, mobilization and public pressure. Boulos has combined street-level activism with electoral politics, becoming a prominent public voice on social inequality in Brazil.

Profile and activity

Boulos is identified with the Brazilian left and has been described as one of its most visible younger leaders. His work with MTST focuses on securing access to housing for low-income families, promoting land regularisation and pressing governments to use vacant properties for social housing. The movement's tactics include organised occupations of unused buildings and public demonstrations aimed at forcing negotiations with authorities.

Political involvement and elections

He joined the Socialism and Liberty Party (PSOL) and became active in electoral politics in the late 2010s. He participated in the 2018 electoral cycle and is associated with the party's national campaigns during that period, including visibility around the 2018 general election. Boulos later stood as a candidate in municipal elections, notably running for mayor of São Paulo, and has used electoral campaigns to broaden debate about housing, public services and social justice.

Impact, controversies and public role

Boulos's combination of direct action and candidacy has made him a polarising figure: supporters praise his commitment to poor urban residents and ability to translate mobilization into public debate, while critics characterise his methods as confrontational or disruptive. He has faced legal actions and arrests related to occupation campaigns, which supporters describe as part of broader struggles for basic rights.

Writing and ideas

In addition to activism, Boulos has written and lectured on urban policy, social movements and political strategy. His public interventions aim to link housing issues to wider themes such as inequality, labour and democratic participation, and to place grassroots struggles within national political conversations.

  • Role: National coordination of MTST, organiser of housing occupations.
  • Political affiliation: PSOL (Socialism and Liberty Party).
  • Public profile: Combines street movement leadership with electoral campaigns and media presence.