Compaq Computer Corporation (sometimes abbreviated to CQ prior to a 2007 rebranding) was an American information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced some of the first IBM PC compatible computers, being the second company after Columbia Data Products to legally reverse engineer the IBM Personal Computer. It rose to become the largest supplier of PC systems during the 1990s before being overtaken by Dell in 2001. Struggling to keep up in the price wars against Dell, as well as with a risky acquisition of DEC, Compaq was acquired for US$25 billion by HP in 2002. The Compaq brand remained in use by HP for lower-end systems until 2013 when it was discontinued. Since 2013, the brand is currently licensed to third parties for use on electronics in Brazil and India.

The company was formed by Rod Canion, Jim Harris, and Bill Murto, all of whom were former Texas Instruments senior managers. Murto (SVP of sales) departed Compaq in 1987, while Canion (president and CEO) and Harris (SVP of engineering) left under a shakeup in 1991, which saw Eckhard Pfeiffer appointed president and CEO. Pfeiffer served through the 1990s. Ben Rosen provided the venture capital financing for the fledgling company and served as chairman of the board for 17 years from 1983 until September 28, 2000, when he retired and was succeeded by Michael Capellas, who served as the last chairman and CEO until its merger with HP.

Prior to its merger, the company was headquartered in northwest unincorporated Harris County, Texas, which now continues as HP's largest United States facility.