Martok
From FEInfobase
Chancellor Martok was the leader of the Klingon Empire, he came to power in 2375.
He oversaw the Klingon people's joining of the Federation and continued to lead his race via the United Federation of Planets. It was under his leadership that the Klingons' dissatisfaction with Federation membership was allayed and appeased. Due to advanced age in 2409, however, Chancellor Martok fell ill, and disappeared from public life and governance. His incapacitation would precipitate the departure of the Klingons from the Federation, and the reformation of the Klingon Empire.
Within a month of falling ill, Martok decreed that he was too old to lead, and too old to search for a suitable death, and so submitted himself to the Hegh'bat, the ritual suicide of the Klingon people.