The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aerospace for the Boeing 777, with thrust ratings from 81,000 to 115,000 pounds-force. It entered service with British Airways in November 1995. It is one of three options for the 777-200, -200ER, and -300 versions, and the exclusive engine of the -200LR, -300ER, and 777F. It was the largest jet engine, until being surpassed in January 2020 by its successor, the 110,000 lbf (490 kN) GE9X, which has a 6-inch (15 cm) larger diameter fan. However, the GE90-115B, the most recent variant, is rated for a higher thrust than the GE9X.

A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a combination of the preceding generation engine technology of the turbojet, and a reference to the additional fan stage added. It consists of a gas turbine engine which achieves mechanical energy from combustion, and a ducted fan that uses the mechanical energy from the gas turbine to force air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust.