Martti Oiva Kalevi Ahtisaari ([mɑrtːi oiʋɑ kɑleʋi ɑhtisɑːri] 23 June 1937 - 16 October 2023) was a Finnish politician, the tenth President of Finland (1994–2000), a Nobel Peace Prize laureate, and a United Nations diplomat and mediator noted for his international peace work.
Ahtisaari was a United Nations special envoy for Kosovo, charged with organizing the Kosovo status process negotiations, aimed at resolving a long-running dispute in Kosovo, which later declared its independence from Serbia in 2008. In October 2008, he was awarded the Nobel Peace Prize "for his important efforts, on several continents and over more than three decades, to resolve international conflicts". The Nobel statement said that Ahtisaari has played a prominent role in resolving serious and long-lasting conflicts, including ones in Namibia, Aceh (Indonesia), Kosovo, and Iraq.
After the death of Mauno Koivisto in May 2017, Martti Ahtisaari became the oldest living President of Finland until his own death in October 2023.
Ahtisaari died from complications of Alzheimer's disease in Helsinki, on 16 October 2023, at age 86. His state funeral was held on 10 November 2023 in Helsinki Cathedral at 1 p.m., after which he was buried at the Hietaniemi Cemetery in Helsinki.