Honoré Mercier (October 15, 1840 – October 30, 1894) was a lawyer, journalist and politician in Quebec, Canada. He was the ninth Premier of Quebec from January 27, 1887 to December 21, 1891, as leader of the Parti National or Quebec Liberal Party (PLQ).

Mercier was born in Saint-Athanase, Lower Canada, studied at the Jesuit College Sainte-Marie in Montreal and was called to the Bar of Quebec in April 1865. As the age of 22, Mercier became the editor of Le Courrier de St-Hyacinthe newspaper. He opposed the Confederation project as early as 1864, believing that it would be detrimental to French Canadians.

In 1871, he was instrumental in creating the short-lived Parti National. Mercier successfully ran as a Liberal candidate in the 1872 election. He became Member of the House of Commons for the district of Rouville. He did not run for re-election in the 1874 election. In the 1878 election, Mercier was candidate in the district of St. Hyacinthe. He was defeated by the Louis Tellier, his Conservative opponent.

Thomas Joseph "Tom" Mulcair (born October 24, 1954) is the Leader of the Official Opposition in Canada, a lawyer, university professor, and politician. A New Democratic Party Member of Parliament for the electoral district of Outremont in Quebec since 2007, he was selected as the leader of the New Democratic Party, thus the Leader of the Official Opposition, in the leadership election on March 24, 2012, with 57.2% of the votes on the fourth and final ballot.

He was the provincial Member of the National Assembly of Quebec for the riding of Chomedey in Laval from 1994 to 2007, holding the seat for the Liberal Party of Quebec. He served as the Minister of Sustainable Development, Environment and Parks from 2003 until 2006, in the Liberal government of Premier Jean Charest. Elected MP for Outremont in a by-election in 2007, he was named Deputy Leader of the New Democratic Party, jointly with Libby Davies, shortly afterwards, and has won re-election twice.

On May 26, 2011, he was named the New Democratic Party's Opposition House Leader. On March 24, 2012, Thomas Mulcair was elected to be the new federal NDP leader, succeeding the late Jack Layton. Prior to entering politics, Mulcair was a senior civil servant in the Quebec provincial government, ran a private law practice, and taught law at the university level.