The Most Reverend Olivier Elzéar Mathieu was born on December 24, 1853 in the parish of St. Roch, Quebec City.  He received his priestly formation at the Quebec seminary and was ordained on June 2, 1878.  A career as seminary professor, superior of the seminary, and finally, Rector of Laval University followed.

On March 4, 1910, the diocese of Regina was erected as a suffragan See of the Archdiocese of St. Boniface, but only on July 21, 1911 was the appointment of its first bishop made.  Olivier Elzéar Mathieu was consecrated in Quebec on November 5, 1911, to be the first non-Oblate bishop in the West.  His installation in Regina took place on November 23 in St. Mary's church, then the only parish in Regina.  

His diocese covered all the southern portion of the province of Saskatchewan, had 60 priests, and served a mixed population of First Nations, Metis, French-Canadian and recently arrived European settlers.

In 1915, the Western dioceses were realigned to coincide with the boundaries of the civil provinces.  Regina became the Metropolitan See of the ecclesiastical province of Saskatchewan, and on December 4, 1915, Bishop Mathieu was elevated to the rank of Archbishop.  

After a tireless and fruitful ministry and a lengthy illness, Archbishop Mathieu died in Regina on October 26, 1929, and was buried from Holy Rosary Cathedral, the diocesan mother church constructed under his auspices in 1913.

This painting of Archbishop Mathieu hangs in Holy Rosary Cathedral, Regina.