Hawker had its roots in the aftermath of the First World War which resulted in the bankruptcy of the Sopwith Aviation Company. Sopwith test pilot Harry Hawker and three others, including Thomas Sopwith, bought the assets of Sopwith and formed H.G. Hawker Engineering in 1920.

In 1933 the company was renamed Hawker Aircraft Limited and took advantage of the Great Depression and a strong financial position to purchase the Gloster Aircraft Company in 1934. The next year it merged with the engine and automotive company Armstrong Siddeley and its subsidiary, Armstrong Whitworth Aircraft, to form Hawker Siddeley Aircraft. This group also encompassed A. V. Roe and Company; Avro.  Hawker Aircraft continued to produce designs under its own name as a part of the Hawker Siddeley Aircraft, from 1955 division of Hawker Siddeley Group. The "Hawker" brand name was dropped, along with those of the sister companies, in 1963. The Hawker P.1127 was the last aircraft branded as "Hawker".

In 1948, the company name was changed to Hawker Siddeley Group. The aircraft division would become Hawker Siddeley Aviation (HSA) and the guided missile and space technology operations as Hawker Siddeley Dynamics (HSD). In 1959, the aero engine business, Armstrong Siddeley was merged with that of the Bristol Aero Engines to form Bristol Siddeley.  In the late 1950s, the British government decided that with the decreasing number of aircraft contracts being offered, it was better to merge the existing companies, of which there were about 15 surviving at this point, into several much larger firms. Out of this decision, came the "order" that all future contracts being offered had to include agreements to merge companies. In 1959, Folland Aircraft was acquired, followed by de Havilland Aircraft Company and Blackburn Aircraft in 1960. In 1963, the names of the constituent companies were dropped, with products being rebranded as "Hawker Siddeley" or "HS". In this period, the company developed the first operational, and, by far, the most successful VTOL jet aircraft, the Harrier family. This aircraft remained in production into the 1990s and remains in service.

The Hawker legacy was maintained by the American company Raytheon who produced business jets (including some derived from the BAe 125, whose original design dated back to de Havilland days) under the "Hawker" name. This was the result of purchasing British Aerospace's product line in 1993. The name is currently used by Hawker Beechcraft after Raytheon's business jet interests (Hawker and Beechcraft) were acquired by investors and merged.

Source: Wikipedia