Sinn Fein's chief negotiator, Martin McGuinness (49), has been a pivotal advocate of the creation of an alternative to the republican armed struggle.
He became involved in the civil rights movement in Derry after October 1968 and joined the republican movement in 1970, becoming its leader in the city and running Free Derry until the British army broke through the barricades in 1972.
Mr McGuinness was arrested in 1972 and 1974 in the Republic and served two terms in prison for IRA membership.
Currently a member of Parliament for the Mid-Ulster constituency, he has refused to take up his seat at Westminster in accordance with the party's policy of abstention. It also refuses to take the oath of allegiance to the Queen.