Berta Isabel Cáceres Flores (Spanish pronunciation: [ˈbeɾtajsaˈβel ˈkaseɾes ˈfloɾes]; 4 March 1971 – 3 March 2016) was a Honduran (Lenca) environmental activist, indigenous leader, co-founder and coordinator of the Council of Popular and Indigenous Organizations of Honduras (COPINH). She won the Goldman Environmental Prize, one of the most prestigious awards for environmental activism, in 2015 for "a grassroots campaign that successfully pressured the world's largest dam builder to pull out of the Agua Zarca Dam" at the Río Gualcarque.

In 2016 she was assassinated in her home by armed intruders, after many years of threats against her life. A former soldier, with the US-trained special forces units of the Honduran military, asserted that Cáceres' name was on their hitlist for months prior to her assassination. As of February 2017, three of the eight arrested people have been linked to the US-trained elite military troops. Two had been trained at Fort Benning, Georgia, USA, at the former School of the Americas (SOA), now known as the Western Hemisphere Institute for Security Cooperation, or WHINSEC. Having been founded in 2001, WHINSEC has since been linked to thousands of murders and human rights violations in Latin America by its graduates. In November 2017, a team of international legal experts released a report finding "willful negligence by financial institutions." For example, the Central American Bank for Economic Integration (CABEI), the Netherlands Development Finance Institution (FMO) and the Finnfund pursued a strategy with shareholders, executives, managers, and employees of the Honduran company Desarrollos Energeticos SA (DESA), private security companies working for DESA, public officials and State security agencies "to control, neutralize and eliminate any opposition".

Twelve land defenders were killed in Honduras in 2014, according to research by Global Witness, making it the most dangerous country in the world, relative to its size, for activists protecting forests and rivers. Berta Cáceres' murder was followed by those of two more activists within the same month.

In July 2021, Roberto David Castillo, the former president of DESA, was found guilty of being a co-conspirator in her murder, and sentenced to 22 and a half years in prison.

Berta Isabel Cáceres Flores was born in La Esperanza, Honduras into the Lenca people, a predominant Indigenous group in southwestern Honduras. The youngest of 12, she grew up in the 1970s during a time of civil unrest and violence in Central America. Her mother Austra Bertha Flores Lopez was a role model of humanitarianism: She was a midwife, assisting in thousands of natural births in the Honduran countryside, and social activist who took in and cared for refugees from El Salvador. Austra Flores was elected and served as a two-term mayor of their hometown of La Esperanza, as a congresswoman, and as a governor of the Department of Intibucá.

After attending local schools, Cáceres studied education at a university and graduated with a teaching qualification. Fr. Ismael Moreno, a priest and director of Radio Progreso & ERIC-SJ, became a close friend and collaborator of Cáceres.

In 1993, as a student activist, Cáceres co-founded the Council of Popular and Indigenous Organizations of Honduras (COPINH), an organization to support indigenous people's rights in Honduras. She led campaigns on a wide variety of issues, including protesting illegal logging, plantation owners, and the presence of US military bases on Lenca land. She supported feminism, LGBT rights, as well as wider social and indigenous issues. Early on in her life of activism, she understood the value and the implications of the LGBT struggle, as she recognized that they experienced the same discrimination and oppression that her and her people did.

In 2006, a group of indigenous Lenca people from Río Blanco asked Cáceres to investigate the recent arrival of construction equipment in their area. Cáceres duly investigated and informed the community that a joint venture project between Chinese company Sinohydro, the World Bank's International Finance Corporation, and Honduran company Desarrollos Energéticos, S.A., also known as DESA, had plans to construct a series of four hydroelectric dams on the Gualcarque River.