Marc Ona Essangui is founder of the environmental NGO Brainforest and president of Environment Gabon, a network of NGOs.

Marc Ona Essangui led efforts to expose agreements behind a Chinese mining project in Gabon, a country in West Central Africa, that threatened equatorial rainforest ecosystems.

According to Ona Essangui, the proposed Belinga development, a $3.5 billion project, was secretly negotiated.

[2] In March 2013, Ona Essangui was sentenced to a six-month suspended prison sentence and an approximately $10,000 USD fine for defamation of Liban Soleman, senior advisor to President Ali Bongo Ondimba.

[3] From January 2020 to July 2023, Marc Ona Essangui was the president of Tournons La Page movement for democracy in Africa.