Nicholas Roland Leybourne Haysom, a distinguished South African diplomat, lawyer, and tireless advocate for peace and justice, passed away on March 19, 2026, in New York City at the age of 73 due to heart and lung complications. Known affectionately as "Fink," a nickname stemming from a hospital mix-up at birth where he was briefly swapped with a baby of a Mrs. Finkelstein, Haysom dedicated his life to democratic governance, constitutional reform, and reconciliation, leaving an indelible mark on his native South Africa and numerous conflict-affected regions across the globe.

Haysom's journey began in the crucible of South Africa's anti-apartheid struggle, influenced by his mother, an activist against apartheid, and a liberal family upbringing in Durban that championed racial equality. Educated at the Universities of Natal and Cape Town, he became a vocal critic of apartheid, serving as president of the National Union of South African Students (NUSAS) in 1976. His activism led to multiple arrests and detentions, including six months in solitary confinement around 1980, experiences that deeply shaped his commitment to human rights and the rule of law.

Following the dismantling of apartheid, Haysom played a pivotal role in South Africa's democratic transition. From 1994 to 1999, he served as the chief legal and constitutional adviser to President Nelson Mandela, contributing significantly to the drafting of the country's new constitution, which enshrined equal rights for all citizens. This period established his reputation as a principled legal mind and a pragmatic political operator, a contribution later highlighted by President Cyril Ramaphosa.

Haysom's expertise in constitutional affairs and peace processes soon drew him to international service. From 1999 to 2002, he was instrumental in the Burundi Peace Talks, chairing the committee negotiating constitutional issues under the facilitation of former President Mandela. He then served as the principal adviser to the Mediator in the Sudanese Peace Process from 2002 to 2005, laying groundwork for future peace agreements.

His distinguished career with the United Nations began in 2005, where he consistently tackled some of the world's most complex and fragile settings. He first headed the Office of Constitutional Support for the UN Assistance Mission in Iraq until 2007, working to foster coexistence among diverse communities. From 2007 to 2012, he served as Director for Political, Peacekeeping and Humanitarian Affairs in the Executive Office of then-UN Secretary-General Ban Ki-moon, demonstrating his broad diplomatic capabilities.

Haysom's leadership was further evident during his tenure as Special Representative of the Secretary-General and Head of the UN Assistance Mission in Afghanistan (UNAMA) from 2014 to 2016. Following this, he served as Special Envoy for Sudan and South Sudan from March 2016 to October 2018, continuing his dedication to regional stability.

From October 2018 to 2019, Haysom took on the challenging role as Special Representative and Head of the UN Assistance Mission in Somalia (UNSOM). His tenure there concluded abruptly when he was ordered to leave Somalia in 2019 after questioning the arrest of a former leader of the al-Shabab extremist group. He then served as Special Adviser on Sudan from 2019 to October 2020, and as Special Adviser for Southern Africa from October 2020 to January 2021.

His final and perhaps most challenging assignment was as the Special Representative of the Secretary-General and Head of the United Nations Mission in South Sudan (UNMISS), a role he assumed in January 2021 and held until his passing. In this capacity, he tirelessly advocated for a peaceful, inclusive, and democratic transition, emphasizing the welfare and aspirations of the South Sudanese people.

Beyond his professional achievements, Haysom was a devoted family man. He was married twice: first to Mary Ann Cullinan, with whom he had two daughters, Rebecca and Simone, and a son, Julian; and subsequently to Delphine, with whom he had two further sons, Charles and Hector. His commitment to justice was also expressed artistically, winning him the South Africa Playwright of the Year award in 1987 for his play 'The Native Who Caused All the Trouble.' In 2012, the University of Cape Town, his alma mater, recognized his intellectual rigor and moral courage by awarding him an honorary doctorate.

Nicholas Haysom was remembered by UN Secretary-General António Guterres as a "principled lawyer, tireless peacemaker, and steadfast champion of the values of the United Nations," whose legacy would endure in the peace processes he advanced and institutions he strengthened. South African President Cyril Ramaphosa mourned him as a "distinguished diplomat and a pioneer of our democratic administration" whose commitment to justice and peace made the world a better place, highlighting his legal acumen, mentorship, wisdom, and integrity. The University of Cape Town also paid tribute to him as a distinguished alumnus, emphasizing his unwavering commitment to justice, while anti-apartheid activist Jay Naidoo recalled Haysom and his first wife as among the first white comrades who treated him as an equal. His profound dedication to justice, dialogue, and reconciliation inspired countless colleagues and left an enduring impact on peace processes and institutions worldwide.