Danno O'Mahoney	1935-07-30	Boston, MA, USA
Reigning New York State Athletic Commission and National Wrestling Association World champion, defeats AWA champion Ed Don George on 35-07-30 in Boston, MA to be the unified champion; loses to Dick Shikat on 36-03-02 in New York, NY but still recognized as champion by AWA in Boston and Montreal.
Yvon Robert	1936-07-16	Montreal, QC
Stripped of AWA title on 38-01 for not meeting Lou Thesz but still recognized as champion in Montreal.
Vic Christy	1938-03-03	Toronto, ON
Don McIntyre	1938-05-06	Buffalo, NY, USA
Vic Christy [2]	1938-05-13	Buffalo, NY, USA
Masked Marvel (Ted Cox)	1938-06-09	Toronto, ON
Yvon Robert [2]	1938-09-14	Montreal, QC
Marvel continues to be recognized in Ontario; Cy Williams defeats Robert on 38-11-28 in Montreal, QC; the decision is later overturned by the Montreal Athletic Commission.
Cy Williams	1938-12-19	Montreal, QC
Stripped in 39-08 when Williams refuses to put up a bond to defend the title.
Ernie Dusek	1939-08-11
Has defeated Danno O'Mahoney in tournament final on 39-08-08 in Montreal, QC to be the top contender for the title; awarded the title when Williams is stripped.
Yvon Robert [3]	1939-10-03	Montreal, QC
Joe Cox	1940-02-27	Montreal, QC
Leo Numa	1940-05-20	Québéc City, QC
Lou Thesz	1940-06-12	Montreal, QC
Yvon Robert [4]	1940-10-23	Montreal, QC
Lou Thesz [2]	1941-07-16	Montreal, QC
Yvon Robert [5]	1941-09-17	Montreal, QC
John Katan	1943-04-15	Montreal, QC
Yvon Robert [6]	1943-04-28	Montreal, QC
Gino Garibaldi	1943-05-12	Montreal, QC
Bobby Managoff	1943-05-19	Montreal, QC
Yvon Robert [7]	1943-09-15	Montreal, QC
Sandor Szabo	1944-03-22	Boston, MA, USA
Yvon Robert [8]	1944-06-14	Montreal, QC
Frank Sexton	1944-07-19	Montreal, QC
Yvon Robert [9]	1944-08-23	Montreal, QC
Gino Garibaldi [2]	1944-11-01	Montreal, QC
Yvon Robert [10]	1944-11-23	Montreal, QC
Joe Savoldi	1945-07-04	Montreal, QC
Bobby Managoff [2]	1945-09-12	Montreal, QC
Lou Thesz [3]	1946-09-11	Montreal, QC
Bobby Managoff [3]	1947-02-20	Ottawa, ON
Lou Thesz [4]	1947-04-16	Montreal, QC
Yvon Robert [11]	1947-11-26	Montreal, QC
Whipper Billy Watson	1949-04-21	Ottawa, ON
Yvon Robert [12]	1949-06-22	Montreal, QC
Bobby Managoff [4]	1950-02-01	Montreal, QC
Yukon Eric	1950-02-15	Montreal, QC
Bobby Managoff [5]	1950-11-08	Montreal, QC
Buddy Rogers	1951-05-09	Montreal, QC
Yvon Robert [13]	1951-07-13	Montreal, QC
Vacant in 52.
Killer Kowalski	1952-04-02	Montreal, QC
Defeats Bobby Managoff.
Verne Gagne	1953-02-25	Montreal, QC
Killer Kowalski [2]	1953-05-06	Montreal, QC
Yvon Robert [14]	1953-07-15	Montreal, QC
Killer Kowalski [3]	1953-08-19	Montreal, QC
Don Leo Jonathan	1953-11-23	Boston, MA
Defeats Kowalski via DQ in what is most likely a non-title match (Boston Herald, 53-11-24) but reported as a title change in Montreal.
Killer Kowalski [4]	1953-12-02	Montreal, QC
Antonino Rocca	1954-05-12	Montreal, QC
Killer Kowalski [5]	1954-05-19	Montreal, QC
Rocca forfeits title when he cannot continue after losing the second fall to even the match at one fall each.
Pat O'Connor	1954-07-21	Montreal, QC
Killer Kowalski [6]	1954-11-10	Montreal, QC
Pat O'Connor [2]	1955-03-09	Montreal, QC
Don Leo Jonathan [2]	1955-06-08	Montreal, QC
Yvon Robert [15]	1955-08-17	Montreal, QC
Don Leo Jonathan [3]	1955-08-24	Montreal, QC
Killer Kowalski [7]	1955-12-14	Montreal, QC
Yvon Robert [16]	1956-04-13	Québéc City, QC
Killer Kowalski [8]	1956-05-30	Montreal, QC
Edouard Carpentier	1956-08-15	Montreal, QC
Killer Kowalski [9]	1956-09-26	Montreal, QC
Edouard Carpentier [2]	1957-05-08	Montreal, QC
Gene Kiniski	1957-06-12	Montreal, QC
Killer Kowalski [10]	1957-07-17	Montreal, QC
Buddy Rogers [2]	1959-09-16	Montreal, QC
Killer Kowalski [11]	1959-12-02	Montreal, QC
Buddy Rogers [3]	1960-01-13	Montreal, QC
Killer Kowalski [12]	1960-06-08	Montreal, QC
Edouard Carpentier [3]	1960-09-21	Montreal, QC
Hans Schmidt	1961-07-20	Montreal, QC
Johnny Rougeau	1961-11-07	Ottawa, ON
Killer Kowalski [13]	1962-07-23	Montreal, QC
Edouard Carpentier [4]	1963-01-30	Montreal, QC
Still champion as of 64-11-04; stripped in 65 after leaving the area.
Hans Schmidt [2]	1965-09-30	Montreal, QC
Defeats Art Thomas in tournament final to win the International Title (The Montreal Star, 65-10-14).
Johnny Rougeau [2]	1965-11-18	Montreal, QC
[...]
Edouard Carpentier [5]	1966-06<
Billed as champion in Montreal, QC (The Montreal Star, 66-06-04).
Hans Schmidt [3]	1966-07-07	Chicoutimi, QC
Edouard Carpentier [6]	1966-10-03	Montreal, QC
Hans Schmidt [4]	1966-11-16	Québéc City, QC
Mad Dog Vachon	1967-01-24	Chicoutimi, QC
Johnny Rougeau [3]	1967-06-05	Montreal, QC
Mad Dog Vachon [2]	1967-08-14	Montreal, QC
Vacant in 67 when Vachon is injured in a car accident.
The Sheik	1967-10-23	Montreal, QC
Defeats Gino Brito after the two have tied for first place in a tournament final on 67-10-16.
Edouard Carpentier [7]	1967-11-06	Montreal, QC
Baron Von Raschke	1967-11-27	Montreal, QC
Johnny Rougeau [4]	1968-02-05	Montreal, QC
Held up after the match against Abdullah the Butcher on 68-12-30 in Montreal, QC.
Johnny Rougeau [5]	1969-02-17	Montreal, QC
Wins rematch.
Ivan Koloff [2]	1969-05-23	Québéc City, QC
Abdullah the Butcher	1969-07-14	Montreal, QC
Jacques Rougeau	1969-08-11	Montreal, QC
Abdullah the Butcher [2]	1969-11-24	Montreal, QC
Johnny Rougeau [6]	1970-03-30	Montreal, QC
Danny Lynch	1970-10-09	Montreal, QC
Johnny Rougeau [7]	1970-12-07	Montreal, QC
Jos LeDuc	1971-04-26	Montreal, QC
Mr. X/Tarzan Zorra	1971-06-21	Montreal, QC
Abdullah the Butcher [3]	1971-08-30	Montreal, QC
Carlos Rocha	1971-12-27	Montreal, QC
The Sheik [2]	1972-05-15	Montreal, QC
Jacques Rougeau [2]	1972-07-17	Montreal, QC
Johnny Valentine	1972-11-27	Montreal, QC
Still champion as of 73-01-08 when Valentine and Jacques Rougeau wrestle to a DDQ.
Jacques Rougeau [3]	1973-01
Awarded sometime before 73-01-11 when Valentine no-shows the rematch; held up or vacant after the match against Waldo Von Erich on 73-02-12 in Montreal, QC ends with DDQ.
Jacques Rougeau [4]	1973-02-19	Montreal, QC
Defeats Waldo Von Erich in rematch.
Dick Taylor	1973-05-07	Montreal, QC
Jacques Rougeau [5]	1973-07-30	Montreal, QC
Wins by default when Taylor no-shows.
Michel Dubois (Alexis Smirnoff)	1973-09-24	Montreal, QC
Sometime after 73-09-09.
The Sheik [3]	1973-12-03	Montreal, QC
Also defeats Grand Prix champion Don Leo Jonathan on 74-04-08 in Montreal, QC (non-title?).
[...]
Tiger Jeet Singh	1974-04-22<
Stripped after no-showing the scheduled title defense against Mad Dog Vachon on 74-07-15 in Montreal, QC.
Abdullah the Butcher [4]	1974-07-22	Montreal, QC
Defeats Tarzan Tyler in a 24-man tournament final; Singh continues to claim the title in Ontario as late as 74-10-21.
Jacques Rougeau [6]	1974-09-09?	Montreal, QC?
Wrestles Abdullah on this day (result unknown) and is billed as champion as of 74-09-23.
Tarzan Tyler	1974-11-04	Montreal, QC
Jacques Rougeau [7]	1975-01-13	Montreal, QC
Still recognized by All Star as of 75-03-25; recognized by Superstar Wrestling from 75-03.
Tarzan Tyler [2]	1975-04-21	Sorel, QC
Result unknown, but Tyler is billed as the champion in the following week.
Johnny Rougeau [7]	1975-09-03	Montreal, QC
Yasu Fuji defeats Rougeau on 75-09-22 in Montreal, QC but the match is not for the title.
Stan Stasiak	1975-10-27	Montreal, QC
Jacques Rougeau [8]	1975-12-01	Montreal, QC
Serge Dumont	1976-03-08	Montreal, QC
Held up after the match against Billy Two Rivers on 76-07-27 in Verdun, QC.
Billy Two Rivers	1976-08-03	Verdun, QC
Wins rematch; held up after the match against Sailor White on 76-10-04 in Montreal, QC.
Sailor White	1976-10-11	Montreal, QC
Wins rematch.
Carlos Rocha	1976-11-29	Montreal, QC
[...]
Johnny Valiant	1977-06<
Dominic DeNucci	1977-07-04	Montreal, QC
Waldo Von Erich	1977-09-26	Montreal, QC
Held up after the match against Spiros Arion on 77-10-10 in Montreal, QC; the rematch on 77-10-17 most likely has no winner.
Spiros Arion	1977-11-07	Montreal, QC
Tarzan Tyler [3]	1978-01-18<
Sometime after 77-12-05; billled as having "recently" defeated Arion (The Montreal Star, 78-01-18); probably awarded after Arion leaves the area in 77-12 or 78-01.
Gino Brito	1978-03-07<
Possibly on 78-02-21 in Verdun, QC although Tyler is still billed as champion in Montreal, QC on on 78-02-27; declared vacant (held up?) after the match against El Santos I on 78-05-03 in Verdun, QC.
Gino Brito [2]	1978-05-10	Verdun, QC
Defeats El Santos I.
[...]
Tarzan Tyler [4]	1979-02-04<
Gino Brito [3]	1979-02-05	Montreal, QC
Still champion as of 79-04-27.
Michel DuBois (Alexis Smirnoff)	1979-04-30?	Montreal, QC?
Recognized by Superstar Wrestling (The Montreal Star, 79-09-01).
Edouard Carpentier [8]	1979-09-03	Montreal, QC
Java Ruuk (Johnny Rodz)	1980-02-11	Montreal, QC

* See also IW International Heavyweight Title.

* Thanks to "cman73" for the additional information.