The lives of a former RUC chief constable and a senior IRA commander feature in a new edition of the Oxford Dictionary of National Biography.
Sir John Hermon was chief constable of the RUC during one of the most turbulent periods of the Troubles.
He was in charge during the 1981 republican hunger strikes and the probes into shoot-to-kill allegations.
Brian Keenan ran the IRA's 1970s English bombing campaign.
He was once called "the biggest single threat to the British state".
Sir John Hermon died in November 2008.
He was in charge when the RUC suffered its biggest single loss of the Troubles, when nine officers were murdered in an IRA mortar attack on Newry police station in 1985.
He remained a target for republicans long after leaving office. He had suffered from Alzheimer's Disease and a year before his death, he had to be moved from a nursing home because of a threat.
The authors of the new Oxford dictionary said his overriding aim from 1980 was to continue the policy of "Ulsterisation", expanding the RUC's capability and acceptability to enable the British army to leave the streets.
"In the mid-1980s Hermon clashed fiercely with John Stalker who led an enquiry into an alleged 'shoot-to-kill' policy.
"Stalker believed Hermon held the line by 'clumsy autocracy' and resented outside interference. Hermon believed that conventional policing standards, as represented by Stalker, were wholly inappropriate in the circumstances then prevailing in Northern Ireland."
Former IRA commander Keenan was among those arrested and imprisoned following the Divis Street riots in 1964.
Four years later he joined the IRA, later identifying his principal motivation as the civil rights movement.
In 1980, he was sentenced to 18 years in prison for conspiracy to cause explosions, but re-joined the IRA army council following his release in the early 1990s.
Though he authorized the 1996 Docklands bombing in London, in July of the following year he supported the calling of a second ceasefire. He was involved in decommissioning talks and took part in weapons talks with Canadian General John de Chastelain, head of the Independent International Commission on Decommissioning
Sinn Fein leader Gerry Adams said Keenan was pivotal in republican moves that made the peace process possible.
"He was central to securing the support of the IRA leadership and rank and file for a whole series of historic initiatives," Mr Adams said at his funeral in May 2008.
The Dublin-born diplomat, academic, journalist and politician Conor Cruise O'Brien and the judge Sir Basil Kelly also feature.
Sir Basil conducted a number of celebrated trials, but one of the most taxing was an important supergrass case in 1983, in which almost 40 defendants were charged with terrorist offences. The atmosphere in court was tense and hostile and he was guarded by armed police officers and wore a flak jacket under his robes.
The Oxford DNB is extended in three annual updates published every January, May, and September.