Episcopal ordinaries •
John Farrell (1856.02.29 – death 28 September 1873), a native of Ireland, consecrated May 11, 1856. He introduced Catholic schools, built St. Mary's Cathedral, and helped to establish the academies of the Ladies of Loretto in Hamilton and Guelph. He also encouraged the founding of St. Jerome's College by the Fathers of the Resurrection, and confided the Owen Sound Missions to the Basilian Fathers. The CRC had been formed in 1836 in Paris. Many of its members were Polish emigres who left their native country in a time of political turmoil. • P. F. Crinnon (1874.02.03 – death November 25, 1882), also born in Ireland and consecrated April 19, 1873. He built St. Patrick's Church in
Hamilton, Ontario, established the House of Providence, Dundas and secured a site for Holy Sepulchre Cemetery. •
James Joseph Carbery (1883.09.04 – death 17 December 1887 in Ireland),
Dominican Order (O.P.) also born in Ireland, consecrated on November 11, 1883, and held an important diocesan synod. •
T. J. Dowling, D.D., first Canadian incumbent (1889.01.11 – death 1924.08.06), previously Bishop of
Peterborough (Canada) (1886.12.14 – 1889.01.11). Since his May 1889 installment, 14 new parishes had been established, 28 priests ordained, and 22 new churches, schools and presbyteries erected. Catholic hospitals at Hamilton and Guelph, and the new House of Providence at Dundas were also established in his time. During Dowling's time, there were 42 priests in the diocese of Canadian by birth. Four were from Ireland, four from the United States, four from France, three from Germany, two from Poland and two from Italy. Candidates for the priesthood studied at St. Jerome's College in Berlin, Ontario (now called
Kitchener,
Ontario) and Grand Seminary in Montreal, Quebec. The diocese had nine parishes for German-speaking people and one Indian parish. There were also chapels for Poles and Italians. •
John Thomas McNally (1924.08.12 – 1937.02.17), previously Bishop of
Calgary (Canada) (1913.04.04 – 1924.08.12); later Metropolitan Archbishop of
Halifax (Canada) (1937.02.17 – 1952.11.18). •
Joseph F. Ryan (1937.08.16 – retired 1973.03.27), died 1990. His term brought much growth and expansion of churches and Catholic schools. •
Paul F. Reding (1973.09.14 – death 1983.12.08) succeeding as previous
Auxiliary Bishop of Hamilton (1966.07.02 – 1973.09.14) and
Titular Bishop of
Liberalia (1966.07.02 – 1973.09.14) •
Anthony F. Tonnos (1984.05.02 – retired on November 8, 2010, after 27 years in the diocese, informally remaining active), succeeding as previous
Auxiliary Bishop of Hamilton (1983.05.13 – 1984.05.02) and Titular Bishop of
Nationa (1983.05.13 – 1984.05.02) •
Douglas Crosby (November 8, 2010 – November 1, 2025), also vice-president of Canadian Conference of Catholic Bishops (2013.09.25 – 2015.09.15), President of Canadian Conference of Catholic Bishops (2015.09.15 – ...); previously Bishop of the Bishop of
Labrador City–Schefferville (Canada) (1997.10.24 – 2007.05.31), Bishop of
Saint George’s (Canada) (2003.08.06 – 2007.05.31), Bishop of
Corner Brook and Labrador (
Newfoundland and Labrador, Canada) (2007.05.31 – 2010.09.24) •
Joseph Dabrowski (February 2, 2026 - ) Previously Bishop of
Charlottetown(Canada) (April 2. 2023-November 1, 2025), auxiliary Bishop of
London (Ontario, Canada)(April 14, 2015 - April 2. 2023) and Titular Bishop of
Casae in Numidia (April 14, 2015 - April 2. 2023)
Auxiliary bishops •
Paul Francis Reding (1966-1973), appointed Bishop here •
James Hector MacDonald (1978-1982),
Titular Bishop of Gibba (1978.02.09 – 1982.08.12); next Bishop of
Charlottetown (Canada) (1982.08.12 – 1991.02.02), Metropolitan Archbishop of
Saint John’s (
Newfoundland, Canada) (1991.02.02 – retired 2000.12.04) •
Anthony Frederick Tonnos (1982-1983), appointed Bishop here •
Matthew Francis Ustrzycki (1985-2007), Titular Bishop of
Nationa (1985.05.10 – ...) •
Gerard Paul Bergie (2005-2010), Titular Bishop of
Tabæ (2005.07.11 – 2010.09.14); next Bishop of
Saint Catharines (Ontario, Canada) (2010.09.14 – ...) •
Daniel Joseph Miehm (2013-2017), appointed Bishop of Peterborough, Ontario; Titular Bishop of
Gor (2013.02.20 – 2017.03.10) •
Wayne Lawrence Lobsinger (2020–present), appointed Bishop of Gemellae in Numidia
Other priests of this diocese who became bishops •
Joseph Anthony O'Sullivan, appointed Bishop of Charlottetown, Prince Edward Island in 1931 •
Joseph Lawrence Wilhelm, appointed Auxiliary Bishop of Calgary, Alberta in 1963 •
John Michael Sherlock, appointed Auxiliary Bishop of London, Ontario in 1974 •
Thomas Christopher Collins, appointed Coadjutor Bishop of Saint Paul in Alberta in 1997; elevated to the rank of Cardinal in 2012 •
Peter Joseph Hundt, appointed Auxiliary Bishop of Toronto, Ontario in 2006 ==Churches==