The Cray-2 is a supercomputer with four vector processors made by Cray Research starting in 1985. At 1.9 GFLOPS peak performance, it was the fastest machine in the world when it was released, replacing the Cray X-MP in that spot. It was, in turn, replaced in that spot by the Cray Y-MP in 1988.

The Cray-2 was the first of Seymour Cray's designs to successfully use multiple CPUs. This had been attempted in the CDC 8600 in the early 1970s, but the emitter-coupled logic (ECL) transistors of the era were too difficult to package into a working machine. The Cray-2 addressed this through the use of ECL integrated circuits, packing them in a novel 3D wiring that greatly increased circuit density.

The dense packaging and resulting heat loads were a major problem for the Cray-2. This was solved in a unique fashion by forcing the electrically inert Fluorinert liquid through the circuitry under pressure and then cooling it outside the processor box. The unique "waterfall" cooler system came to represent high-performance computing in the public eye and was found in many informational films and as a movie prop for some time.

Unlike the original Cray-1, the Cray-2 had difficulties delivering peak performance. Other machines from the company, like the X-MP and Y-MP, outsold the Cray-2 by a wide margin. When Cray began development of the Cray-3, the company chose to develop the Cray C90 series instead. This is the same sequence of events that occurred when the 8600 was being developed, and as in that case, Cray left the company.