Intelsat, S.A. is a communications satellite services provider. Originally formed as International Telecommunications Satellite Organization (ITSO, or INTELSAT), it was—from 1964 to 2001—an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast services.

As of March 2011, Intelsat operates a fleet of 52 communications satellites, which is one of the world's largest fleet of commercial satellites. They claim to serve around 1,500 customers and employ a staff of approximately 1,100 people.

The intergovernmental organization (IGO) began on 20 August 1964, with 11 participating countries. On 6 April 1965, Intelsat’s first satellite, the Intelsat I (nicknamed Early Bird), was placed in geostationary orbit above the Atlantic Ocean by a Delta D rocket.

In 1973, the name was changed and there were 80 signatories. Intelsat provides service to over 600 Earth stations in more than 149 countries, territories and dependencies. By 2001, INTELSAT had over 100 members. It was also this year that INTELSAT privatized and changed its name to Intelsat.

Since its inception, Intelsat has used several versions (blocks) of its dedicated Intelsat satellites. Intelsat completes each block of spacecraft independently, leading to a variety of contractors over the years. Intelsat’s largest spacecraft supplier is Space Systems/Loral, having built 31 spacecraft (as of 2003), or nearly half of the fleet.

The network in its early years was not as robust as it is now. A failure of the Atlantic satellite in the spring of 1969 threatened to stop the Apollo 11 mission; a replacement satellite went into a bad orbit and could not be recovered in time; NASA had to resort to using undersea cable telephone circuits to bring Apollo's communications to NASA during the mission. Fortunately, during the Apollo 11 moonwalk, the moon was over the Pacific Ocean, and so other antennas were used, as well as INTELSAT III, which was in geostationary orbit over the Pacific.

By the 1990s, building and launching satellites was no longer exclusively a government domain and as country-specific telecommunications systems were privatized, several private satellite operators arose to meet the growing demand. In the U.S., satellite operators such as PanAmSat, Orion Communications, Columbia Communications, Iridium, Globalstar, TRW and others formed under the umbrella of the Alliance for Competitive International Satellite Services (ACISS) to press for an end to the IGOs and the monopoly position of COMSAT the US signatory to Intelsat and Inmarsat. In March 2001, the US Congress passed the Open Market Reorganization for the Betterment of International Telecommunications (ORBIT) Act to privatize COMSAT and reform the role of the international organizations. In April 1998, to address US government concerns about market power, Intelsat's senior management spun off five of its older satellites to a private Dutch entity, New Skies Satellites, which became a direct competitor to Intelsat. To avert the US government's interference with Intelsat, Intelsat's senior management unsuccessfully considered relocating the IGO to another country.

On 18 July 2001, Intelsat became a private company, 37 years after formation. Prior to Intelsat's privatization in 2001, ownership and investment in INTELSAT (measured in shares) was distributed among INTELSAT members according to their use of services. Investment shares determined each member’s percentage of the total contribution needed to finance capital expenditures. The organization’s primary source of revenue was satellite usage fees which, after deduction of operating costs, was redistributed to INTELSAT members in proportion to their shares as repayment of capital and compensation for use of capital. Satellite services were available to any organization (both INTELSAT members and non-members), and all users paid the same rates.

Today, the number of Intelsat satellites, as well as ocean-spanning fibre-optic lines, allows rapid rerouting of traffic when one satellite fails. Modern satellites are more robust, lasting longer with much larger capacity.

Intelsat Americas-7 (known formerly as Telstar 7 and now known as Galaxy 27) experienced a several-day power failure on 29 November 2004. The satellite returned to service with reduced capacity.

Intelsat was sold for U.S. $3.1bn in January 2005 to four private equity firms: Madison Dearborn Partners, Apax Partners, Permira and Apollo Global Management. The company acquired PanAmSat on 3 July 2006, and is now the world's largest provider of fixed satellite services, operating a fleet of 52 satellites in prime orbital locations. In June 2007 BC Partners announced they had acquired 76 percent of Intelsat for about 3.75 billion euros.

In April 2013, the renamed Intelsat S.A. undertook an initial public offering on the New York Stock Exchange, raising a net $550 million USD, of which $492 million was paid immediately to reduce outstanding company debts of $15.9 billion USD. In May, the company announced it would be purchasing four new high-performance Boeing EpicNG 702 MP satellites.

There were talks that Intelsat was to merge with Softbank-backed OneWeb. However, on 1 June 2017 it was announced that the bondholders would not accept the offer and the merger would be terminated as of 2 June 2017.

Intelsat maintains its corporate headquarters in Luxembourg, with a majority of staff and satellite functions — administrative headquarters — located at the Intelsat Corporation offices in Tysons Corner, Virginia. A highly international business, Intelsat sources the majority of its revenue from non-U.S. located customers. Intelsat's biggest teleport is the Teleport Fuchsstadt in Germany.

As of March 2011, Intelsat has agreed to purchase one-half of the 2,000 kilograms (4,400 lb) propellant payload that an MDA Corporation spacecraft satellite-servicing demonstration project would take to geostationary orbit. Catching up in orbit with four or five Intelsat communication satellites, a fuel load of 200 kilograms (440 lb) of fuel delivered to each satellite would add somewhere between two and four years of additional service life. A near-end-of-life Intelsat satellite will be moved to a graveyard orbit 200 to 300 kilometres (120–190 mi) above the geostationary belt where the refueling will be done, "without consequence" to the Intelsat business.

As of March 2010, the business model was still evolving. MDA "could ask customers to pay per kilogram of fuel successfully added to [each] satellite, with the per-kilogram price being a function of the additional revenue the operator can expect to generate from the spacecraft’s extended operational life."

The plan is that the fuel-depot vehicle would maneuver to several satellites, dock at the target satellite’s apogee-kick motor, remove a small part of the target spacecraft’s thermal protection blanket, connect to a fuel-pressure line and deliver the propellant. "MDA officials estimate the docking maneuver would take the communications satellite out of service for about 20 minutes."

On February 1, 2007, Intelsat changed the names of 16 of its satellites formerly known under the Intelsat Americas and PanAmSat brands to Galaxy and Intelsat, respectively.

Over time, Intelsat has worked with most of the commercial launch services providers worldwide. Their satellites are often among the most massive of their generation, requiring the most powerful and reliable rockets on the market at a given time. In the 21st century, most Intelsat missions were conducted by Arianespace with the European Ariane 4 and Ariane 5 launchers, and by ILS with Proton-K and Proton-M rockets manufactured by Khrunichev in Russia. Intelsat also took advantage of the equatorial Sea Launch offering with Zenit-3SL rockets launched from the Ocean Odyssey floating platform, until they suspended operations in 2014. On May 30, 2012, Intelsat signed a contract with SpaceX for one of the first Falcon Heavy launch vehicles, marking the return of Intelsat to American launchers after many flights on Atlas II in the 1990s and a single Atlas V launch in 2009.

Coordinates: 38°56′30″N 77°03′49″W / 38.94167°N 77.06361°W / 38.94167; -77.06361