Getúlio Vargas, President of Brazil at the time, committed suicide. It wasn't exactly a Führerbunker situation, but things weren't (as should be relatively unsurprising in postwar Latin America) exactly politically settled at that moment--generals were stirring up and demanding resignations.

As the Wikipedia article correctly notes, it actually had some notable political effects in shaming his adversaries.

Lazarus Salii, the third president of the Republic of Palau and one of the nation's founding fathers, committed suicide in 1988, while he was still president. There were bribery allegations at the time, but given that Palau's previous president had been assassinated, there was a great deal of confusion and controversy among Palauans at the time. A lot of the reaction is probably typical of reaction to any suicide -- people didn't believe he was the sort of person who would take his own life, they didn't see the warning signs, and so on. However, my understanding is that signs do point to it being a suicide.

Salvador Allende, leader of Chile from 1970 to 1973, may have committed suicide, although not under exactly peaceful conditions, but still not from war. It's debated whether he actually committed suicide, especially since he gave a speech the day before vowing not to give up his position to a military junta that would later rule Chile with Augusta Pinochet as its leader. Whether or not he did actually commit suicide doesn't matter much anyways, it was still provoked by the CIA-backed junta.

I mean obviously I'm not talking about Hitler at the end of WW2; he had an arguably good reason to go out when he did.

Well it also wasn't peace-time when Hitler suicided.

I've removed this question as it breaches our rule against 'throughout history' questions.