TransCanada Corporation is a major North American energy company, based in Calgary, Alberta, Canada, developing and operating energy infrastructure in North America. Its pipeline network includes approximately 3,460 kilometres (2,150 miles) of oil pipeline, plus approximately 57,000 kilometres (35,418 miles) of wholly owned and 11,500 kilometres (7,146 miles) of partially owned gas pipeline that connects with virtually all major gas supply basins in North America. TransCanada is one of the continent’s largest providers of gas storage and related services with approximately 653 billion cubic feet (1.85×10 m) of storage capacity. TransCanada also owns, or has interests in, approximately 11,800 megawatts of power generation.

TransCanada is the largest shareholder in, and owns the general partner of, TC PipeLines. The company was founded in 1951 in Calgary. In January 2014, 46% of the ownership of TransCanada was by institutional shareholders.

Wholly owned pipelines:

Affiliated pipelines:

TransCanada maintains that people have public access to the pipeline, thus supporting criteria for eminent domain. "It's open for anyone to do business on our pipeline, we welcome business to our pipe." said TransCanada Media Relations Michael Barnes.

At one point in October 2011, TransCanada was involved in up to 56 separate eminent domain actions against landowners in Texas and South Dakota who have refused to give permission to the company to build the Keystone Pipeline on their land. However, on August 23, 2012, Texas Judge Bill Harris ruled that TransCanada has the legal right of eminent domain and may lease or purchase land from owners who refused to sign an agreement with the company for the public right-of-way of a pipeline. The landowners had claimed that because the pipeline was not open to other companies, it did not meet the criteria for eminent domain.

On September 27, 2012, protesters began tree sitting in the path of the Keystone pipeline near Winnsboro, Texas. Eight people stood on tree platforms just ahead of where crews were cutting down trees to make way for the pipeline.

On October 4, 2012, actress and activist Daryl Hannah and 78-year-old Texas landowner Eleanor Fairchild were arrested for criminal trespassing and other charges after they were accused of standing in front of TransCanada pipeline construction equipment on Fairchild's farm in Winnsboro, a town about 100 miles east of Dallas. Ms. Fairchild has owned the land since 1983 and refused to sign any agreements with TransCanada. Her land was seized by eminent domain.

On April 2, 2016, a resident near Freeman, South Dakota observed a leak along the Keystone pipeline. The size and cause were not immediately known.

In June 2012 it was announced that TransCanada was selected by Shell and partners Korea Gas Corporation, Mitsubishi Corporation and PetroChina Company Limited to design, build, own and operate the Coastal GasLink pipeline between northeastern B.C. oil fields near Dawson Creek, British Columbia and an LNG facility export facility on the Douglas Channel near Kitimat, British Columbia.

In January 2013 it was announced that TransCanada was selected by Petronas to design, build, own, and operate the Prince Rupert Gas Transmission project, a gas pipeline that would transport natural gas from the Montney region near Fort St. John, British Columbia to a LNG terminal planned by Progress Energy Canada Ltd. in Port Edward, British Columbia on Lelu Island near Prince Rupert, British Columbia.

TransCanada's existing NGTL system in northeastern B.C. will be expanded and integrated into the new export pipeline systems.

In October 2012, TransCanada formed a 50-50 CAD$3bn joint-venture with Phoenix Energy Holdings Ltd. (the Canadian subsidiary of PetroChina) to develop the 500 km Grand Rapids Pipeline.

TransCanada also owns, or has interests in, approximately 11,800 megawatts of power generation.

Economic withholding is defined as the practice of submitting blocks of electricity at high, non-competitive prices that effectively reduces or withholds the quantity of supply offered at competitive prices. Generators "offer their available electricity to the market for dispatch on the grid" but they raise the price so high the electricity is not dispatched. In this way economic withholding is "an exercise of market power" which intentionally raise prices above competitive levels.

In Alberta, Canada, through the practice of economic withholding a single electricity provider drove up prices on four occasions in May and June, of 2015 during a period of surplus power supply.

Power generators are required to offer their available electricity to the market for dispatch on the grid, but they can choose the price they want for it. If it is priced too high, it might not be dispatched.

A single market participant, TransCanadaEnergy Ltd successfully withheld "much of its available power output on four occasions in May and June 2015 despite there being a surplus supply of power. In response to concerns about the spike in the price of electricity TransCanada's Davis Sheremata claimed that the company "applies our view of prevailing market fundamentals when offering power into the wholesale market."

In June 2010, TransCanada was embroiled in a controversy surrounding a plan to construct a 975 MW gas-fired power plant on a disused 13.5-acre (5.5 ha) portion of Ford's Oakville, Ontario assembly plant. Local residents and politicians have expressed health and safety concerns to Ford in opposition to the plan.

Citing the 2010 gas-fired power-plant explosion plant in Middletown, Connecticut, U.S., and the 2008 Toronto propane explosion, Oakville MPP Kevin Flynn introduced a private member's bill that would require a 1500-meter buffer zone for such a plant, a proposal intended to effectively prevent the construction of this project.

The proposed Oakville site was ultimately abandoned in response to political pressure; the station will instead be built on the Lennox Generating Station site west of Bath, Ontario.

Members of the board of directors of TransCanada are S. Barry Jackson (Chair), Russ Girling (President and CEO), Kevin E. Benson, Derek Burney, John Richels, Paule Gauthier, Paula Rosput Reynolds, Mary Pat Salomone, W. Thomas Stephens, D. Michael G. Stewart and Richard E. Waugh.

In 2014, Transcanada sponsored the Grand Final event held in Edmonton, Alberta, Canada for the 2014 ITU World Triathlon Series. In 2015 the company was a major sponsor for the 2015 World U-17 Hockey Challenge held in Dawson Creek and Fort St. John, British Columbia. Transcanada committed $25,000 in sponsorship funding to assist the Michigan Department of Natural Resources in the maintenance of the Iron Belle Trail. The company adopted a 2 kilometres (1 mile) long stretch of the trail in Kalkaska County, Michigan near an ANR Pipeline facility.