Joseph-Octave Plessis was a priest, first archbishop of diocese of Quebec, politician and author. He was ordained in 1786. Installed as archbishop in 1806 and served until 1825. Bishop Plessis was the first to introduce Christianity into the Red River territory, and founded religious and educational institutions in Upper Canada and the provinces along the Gulf of St. Lawrence. When the English government tried to force a union between Upper and Lower Canada, his energetic resistance helped ensure the plan's failure. He successfully resisted efforts to weaken the force of French-Canadian nationality through the medium of a system of popular education. The colleges of Nicolet and St. Hyacinth were founded through his encouragement. He spent his time and income in searching out young men and educating them at his own expense. Some of the most eminent men of Canada owed their training to him. The passage of the education law of 1824 was to a great extent his work, and his correspondence with Lord Bathurst on this subject proved him a man of great diplomatic force.

From Wikipedia (English):

Joseph-Octave Plessis (March 3, 1763 – December 4, 1825) was a Canadian Roman Catholic clergyman from Quebec. He was the first archbishop of the Roman Catholic Archdiocese of Quebec after the diocese was elevated to the status of an archdiocese.

Plessis cultivated a new generation of priests during the difficult period leading up to the Lower Canada Rebellion, including Jean-Baptiste-Antoine Ferland, Narcisse-Charles Fortier, Jean-Baptiste Kelly, Thomas Maguire, and Pierre-Antoine Tabeau.

Sources: http://www.biographi.ca/en/bio.php?id_nbr=3076