The Bombardier Challenger 600 series is a family of business jets developed by Canadair after a Bill Lear concept, and then produced from 1986 by its new owner, Bombardier Aerospace. At the end of 1975, Canadair began funding the development of LearStar 600, and then bought the design for a wide-cabin business jet in April 1976. On 29 October, the programme was launched, backed by the Canadian federal government, and designed to comply with new FAR part 25 standards.

In March 1977, it was renamed the Challenger 600 after Bill Lear was phased out, and the original conventional tail was changed for a T-tail among other developments. The first prototype was rolled out on 25 May 1978, and performed its maiden flight on 8 November. The flight test program saw a deadly crash on 3 April 1980, but Transport Canada approved the CL-600 type certification on 10 August 1980.

In 1986, Canadair was close to bankruptcy and was bought by Bombardier. The jet was later stretched into the Bombardier CRJ regional airliner, introduced on 19 October 1992, and the longer range Global Express, introduced in July 1999. The 500th Challenger was rolled out in May 2000, and the 1000th was delivered to NetJets in December 2015. By October 2018, 1,066 aircraft had been built.

The Challenger is a low-wing jet powered by two turbofans mounted in aft fuselage pods, with a supercritical wing and a stand-up cabin with two seating sections. The original Lycoming ALF 502 turbofans were replaced by a pair of General Electric CF34s on the CL-601, which also gained winglets, and first flew on 10 April 1982. Subsequent variants have updated systems, avionics, and higher weights.

Around 1974, American aviation inventor Bill Lear conceptualised the LearStar 600, a low-wing, long-distance business jet, which was powered by a pair of Garrett TFE731-1 geared turbofan engines and equipped with a supercritical wing. Lear lacked the capabilities to launch such an aircraft, thus sought out other agencies to collaborate with to both produce and sell it, including the Canadian aerospace manufacturer Canadair. According to authors Ron Picklet and Larry Milberry, Canadair's top management were of the opinion that Lear's concept was sketchy at best. Lear did not have an expert grasp of aeronautical engineering; so far, he had only been able to pay an American aeronautical consultant to undertake very preliminary design explorations.

Following a study, contrasting the proposed Learstar against rivals such as the Lockheed Jetstar, Dassault Falcon 50, and Grumman Gulfstream II, Canadair decided to give its backing to the idea near the end of 1975. According to aerospace industry publication Flight International, the programme was viewed by many Canadians as a step towards developing a privately driven high-technology aviation industry that would compete at a global level. Perhaps more importantly, the Canadian government had issued a demand that Canadair become self-sufficient, thus the company wanted to depend less upon subcontracting arrangements with other firms, such as France's Dassault Aviation and America's Boeing, or providing support packages for existing aircraft for which they had already ended production, such as the CF-5 fighter. Canadair felt a need to prove its ability to independently develop original high-tech projects at this time.

Canadair planned to use Lear's name and skills at self-promotion to secure extensive financial guarantees for a business-jet project from the Canadian federal government. This proved an effective choice: Future Prime Minister Jean Chrétien specifically refers to the effect of personal contact with Lear on his decision to direct financial support to Canadair's program. At the time of these events, Chrétien was successively president of the Treasury Board, minister of Industry, Trade, and Commerce, and minister of Finance, in the Canadian government. Due to the use of letters of comfort, the extent of the ministry's financial commitments for Canadair could be kept from parliament and the public for several years. These financial guarantees were later used as an academic example of insufficient monitoring and lax controls in government support of industry.

In April 1976, Canadair acquired the LearStar 600 concept. By then it was 63 ft (19 m) long, and 53.3 ft (16.2 m) wide, and capable of a maximum speed of Mach 0.85 and a range of 7,240 km (3,910 nmi). As an executive jet, it had sufficient capacity for 14 passengers. In a freighter configuration, it had a 3,400 kg (7,500 lb) payload capacity, loaded and unloaded through a forward door. As a commuter airliner, it could seat up to 30 passengers in a 2–1 seating configuration. Canadair developed the design into a large airframe, furnished with a new supercritical wing design, new avionics and engines, as well as for compliance with new FAR part 25 standards. The configuration was frozen in August and a 1/25 model was tested in the National Aeronautical Establishment transonic wind tunnel. Reportedly, in excess of 1,800 hours of wind tunnel testing were performed upon the supercritical wing alone.