Thomas Edward (Tom) Siddon (born November 9 1941) is a former Canadian politician.

Born in Drumheller, Alberta Siddon pursued engineering, eventually earning a doctorate in aero-acoustics . He became a professor at the University of British Columbia and founded an aero-acoustics firm. Entering politics he was first elected to parliament in a 1978 election to represent the riding of Burnaby—Richmond—Delta .

Under Mulroney's leadership he became the science critic in the shadow cabinet, and after the Tories won the 1984 Canadian election he was given the minor cabinet post of Secretary of State for Science and Technology . There he ran into some controversy when the new government failed to live up to its election promise to double government and private sector research and development funding.

Despite this he proved a hard working and competent MP and was promoted to the Minister of Fisheries and Oceans position on November 21, 1985, in the wake of the tunagate scandal that had forced the resignation of previous minister John Fraser.

Siddon remained in the Fisheries post for five years, until 1990, overseeing one of the most important eras in Canadian fishing history. By the mid-1980s it was evident that severe overfishing was soon going to have consequences. Siddon thus attempted to impose stiff quotas, despite the protests of fishers and the destruction of whole communities as fish processing plants closed throughout the Atlantic provinces. Siddon's policies were the focus of frequent protests and he became drastically unpopular on the east coast. In retrospect it can be seen that Siddon did not go far enough, and in 1991 a complete moratorium on cod fishing had to be imposed as the Canadian fishing industry all but collapsed.

As a result of his unpopularity he was somewhat demoted to the Minister of Indian Affairs and Northern Development position. Again Siddon found himself in the midst of controversy and crisis. Only months after his swearing in the Oka Crisis broke out, and Siddon was attacked for his inactivity and refusal to negotiate until the Mohawks dropped their arms and removed the barricades. Soon after the exclusion of the First Nations from the constitutional process was one of the deciding factors in the death of the Meech Lake Accord. His greatest legacy and success was also achieved as Minister of Indian Affairs when with the agreement to create the new territory of Nunavut in 1992.

With fellow British Columbian and ally Kim Campbell becoming Prime Minister Siddon was promoted to the senior cabinet, becoming Minister of National Defence on June 25, 1993. Once again controversy seemed to dog Siddon as in September the Somalia Affair, almost certainly the greatest scandal in Canadian military history, broke out. Siddon also drew heavy fire for the purchase of new navy helicopters at a cost of billions of dollars without a proper bidding process.

Siddon entered the 1993 election expecting a tough battle. His support for Native landclaims and his earlier fishing quotas had made him on of the top targets of the new Reform Party of Canada. As the campaign progressed it looked increasingly evident that Siddon would lose. At one rally, held jointly with Kamloops candidate Frank Coldicott , only a single person showed up. Siddon ended up finishing third behind Raymond Chan of the Liberals and Nick Loenen of Reform.

Siddon returned to the private sector, but has remained active in Tory politics. He supported Joe Clark's leadership bid in 1998 and later became an early advocate of union between the Tories and Canadian Alliance.