Aerospace

• Avro Canada – airplane manufacturer, maker of the Avro Arrow and the Avro Aerocar.
• Canadair – acquired by Bombardier
• de Havilland Canada – acquired by Boeing and a few years later acquired by Bombardier
• Spar Aerospace – split up and acquired by MacDonald Dettwiler, L-3 Communications and Bombardier

Airlines

• Air Atlantic
• Air BC – merged with Air Canada Jazz
• Air Ontario – merged with Air Canada Jazz
• AllCanada Express
• Austin Airways – acquired by Air Ontario
• Canada 3000 – folded, discount airline
• Canadian Airlines – acquired by Air Canada
• Canadian Pacific Airlines – acquired by Canadian Airlines
• Canadian Regional Airlines – merged with Air Canada Jazz
• Eastern Provincial Airways – acquired by Canadian Pacific Airlines
• Globemaster Air Cargo
• Great Lakes Airlines (Canada) – acquired by Air Ontario
• Greyhound Air
• Harmony Airways
• Inter-Canadien
• Jetsgo
• Lamb Air
• Maestro
• Nationair
• Nolisair
• NorOntair
• North Canada Air – acquired by Time Air
• Pacific Western Airlines
• Peace Air
• Quebecair Express
• Queen Charlotte Airlines – acquired by Pacific Western Airlines
• QuikAir
• Roots Air
• Royal Aviation – acquired by Canada 3000
• Sonicblue Airways
• Southern Frontier Airlines – acquired by Time Air
• Time Air – acquired by Air Canada Jazz
• Trans-Provincial Airlines – acquired by Harbour Air
• Triton Airlines
• Val Air
• Vision Airways Corporation
• Vistajet
• WardAir – acquired by Canadian Airlines
• Winnport
• World-Wide Airways
• Zip – merged with Air Canada
• Zoom Airlines

Banking, finance and insurance

• Bank of America Canada – subsidiary of the United States-based bank chain Bank of America
• Bank of British Columbia (1862) – acquired by Canadian Commercial Bank
• Bank of British Columbia (1978) – acquired by HSBC Bank Canada
• Bank of British North America – acquired by Bank of Montreal
• Bank of Hamilton – acquired by Canadian Imperial Bank of Commerce
• Bank of New Brunswick – acquired by Bank of Nova Scotia
• Bank of Upper Canada
• Canada Trust – acquired by Toronto-Dominion Bank
• Canadian Commercial Bank
• City Bank
• Consolidated Bank of Canada
• Continental Bank of Canada – acquired by Lloyds Bank of Canada
• Home Bank of Canada – failed in 1923
• Lloyds Bank of Canada – acquired by HSBC Bank Canada
• Maritime Life – acquired by Manulife Financial
• Royal Trust – acquired by Royal Bank of Canada

Biotech, medical

• DVS Sciences – acquired by Fluidigm (2014) and changed their name to Standard BioTools (2022)

Computer hardware and software

• AliasWavefront – developers of industry leading Maya 3D software; in 2006 it was bought out by Autodesk Inc.
• ATI Technologies – bought out by AMD
• Ferranti-Packard – early mainframe systems
• HCR Corporation – early Unix company, acquired by Santa Cruz Operation, later closed
• I. P. Sharp Associates – time share company
• Imanet – international trade software
• Sitebrand – online marketing company
• Watcom International Corporation – acquired by Sybase

Consumer retail, including grocery

• Aeropostale Canada – subsidiary of the United States-based retailer Aeropostale, closed all 41 stores in Canada in 2016
• A&A Records – founded in Toronto at the end of WWII, it was the dominant record chain store in Canada until being superseded by Sam the Record Man in the 1960s; it became defunct in 1993
• A&B Sound – home electronics retailer based in Richmond, BC; founded in 1959, it had expanded as far as Winnipeg, Manitoba by 2000, but its subsequent decline saw the company go bankrupt by 2008
• Bata Shoes – shoe retailer and manufacturer
• Beaver Lumber – hardware/lumber store chain; acquired by Home Hardware
• Big Lots Canada
• Dominion – grocery store chain
• Bi-Way – discount store chain
• Eaton's – bankrupt, assets acquired by Sears Canada
• Express – subsidiary of the United States-based clothing retailer Express, closed all 17 stores in Canada in 2017
• Food City – grocery store chain
• Granada TV Rental- electronic consumer goods retail rental outlets
• Hard Rock Cafe -all Canadian Cafe locations closed by 2017 but Hard Rock Casino still exist in Coquitlam, BC, Vancouver, BC, and a new location is set to open in Ottawa in 2021 Hard Rock Cafe still has a location in Niagara Falls, Ontario in Canada.
• HMV Canada – entertainment media chain owned by Hilco; originally a subsidiary of England-based retailer HMV; closed all stores in April 2017, the majority of locations became Sunrise Records
• Kmart Canada – subsidiary of US chain, some assets acquired by Zellers
• Knob Hill Farms – grocery store chain
• Kresge (Canadian division) – discount store chain
• Lumberland Building Materials (BC-based store founded in Surrey; it merged with Revy Home Centres in 1997,^[2] which then was acquired by Rona in 2001)
• LW Stores – discount store chain; acquired by Big Lots in 2010 and closed all stores in 2014
• Marks & Spencer – major British retailer; had operated in Canada since 1973; closed all Canadian operations by 1999^[3]
• Miracle Mart – discount store owned by the Steinberg family
• Miracle Food Mart – grocery store chain
• Morgan's – department store chain
• Pascal – bankrupt in 1991 (Hardware Stores) – 1994 (furniture stores) – 2008 (Pascal Hotel Supplies)
• RadioShack Canada – renamed The Source by Circuit City in 2005
• Revelstoke Home Centres Ltd. (aka Revy's or Revy Home Centres; owned by the West Fraser Timber Company, this was a major home improvement retailer headquartered in Revelstoke, BC; merged with Rona in 2001^[4])
• Sam The Record Man – record/entertainment media stores
• Sam's Club Canada – warehouse store chain and the subsidiary of Walmart Canada; closed in 2009
• Sears Canada – department store chain and the Canadian subsidiary of the American-based Sears, all stores closed in January 2018
• Shoprite Catalogue order store, went bankrupt in 1970s.
• Simpsons – department store chain (AKA Simpson's Sears and Sears Roebuck)
• Steinberg's – grocery store chain
• Target Canada – Canadian subsidiary of the American-based department store chain Target Corporation, closed all stores in 2015
• Thrifty's – denim/clothing store
• Towers – department store chain
• Toy City – a toy store chain, a subsidiary of Consumers Distributing
• Woodward's – department store chain
• Woolco – discount department store, acquired by Wal-Mart providing an expansion route into the Canadian market
• Zellers – discount department store; store properties bought by Target Corporation and most converted into Target Canada stores

Food and beverage

• Mitchell's Gourmet Foods – acquired by Maple Leaf Foods
• Mother's Pizza (Chain is in the process of being revived)

Mining and energy

• Bre-X – gold mining company, collapsed in fraud
• Dominion Steel and Coal Corporation
• Eldorado Resources – uranium mining, merged with Saskatchewan Mining Development Corporation to form Cameco (1988)
• Gulf Canada Resources – acquired by Conoco
• Hudson Bay Mining and Smelting Co. – mining
• Lightstream Resources Ltd. – oil and gas (dissolved under corporate legislation)
• Noranda – mining, merged with Falconbridge Ltd. (2005)
• Saskatchewan Mining Development Corporation (SMDC) – uranium mining, merged with Eldorado Mining and Refining Limited to form Cameco (1988)
• Teck Cominco – mining
• Westcoast Energy – acquired by Duke Energy
• West Kootenay Power & Light – acquired by Fortis Inc

Railways, commuter rail and steamship companies

Telecommunications companies

• Nortel – established in 1895; in 2000 accounted for more than a third of the total valuation of all the companies listed on the Toronto Stock Exchange (TSX)